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DEEP BOREHOLE SURVEYS 
AND PROBLEMS 



BOOKS BY THE SAME AUTHOR 

MINE VENTILATION AND VENTILATORS 

{Charles Griffin & Co., Ltd., London) 

LOCATION OF MINERAL FIELDS 

{Crosby, Lockwood & Sons, London) 

DISRUPTED STRATA 

{Crosby, Lockivood & Sons, London) 



DEEP BOREHOLE SURVEYS 
AND PROBLEMS 



BY 
M. H. HADDOCK, F.G.S., A.M.I.Min.E. 

Principal, The Alining and Technical Institute, 
Coalville, Leicester, England 




First Edition 



McGRAW-HILL BOOK COMPANY, Inc. 

NEWYORK AND LONDON 
1931 



Copyright, 1931, by the 
McGraw-Hill Book Company, Inc. 



PRINTED IN THE UNITED STATES OF AMERICA 

All rights reserved. This hook, or 

parts thereof, may not be reproduced 

in any form ivithout permission of 

the publishers. 



THE MAPLE PRESS COMPANY, YORK, PA. 



PREFACE 

The amount of trouble, litigation and random specula- 
tion that could be avoided by a correct knowledge of the 
course of deep boreholes is immeasurably great. It is 
generally agreed among those most concerned that the 
deep borehole which does not deviate from its intended 
direction has yet to be bored. Bearing these significant 
facts in mind I have attempted in the following pages to 
trace the evolution of modern borehole-surveying devices 
and add various problems relevant to strata location and 
orientation. 

Since most of the world's deep borehole projects are 
outside the British Empire I have supplemented my 
experience and observations by information from many 
and varied sources. In this respect I have been most 
generously aided by many workers in America, Germany, 
Russia and elsewhere, and I hope these are all sufficiently 
acknowledged where the respective transcriptions appear 
in the text. In particular I am indebted to the several 
acute and vigorous bodies of oil-field investigators centered 
about Oklahoma and the Gulf Coast in America and the 
Rumanian societies on this side. Some methods of bore- 
hole exploration have not been dealt with here either 
because they are shrouded in commercial secrecy or because 
they do not appear to add very materially to the advance- 
ment of the art. 

Generally speaking the present geological engineer does 
not seem to be enamored of the highly ingenious and exact 
suite of post-war instruments, being in many cases content 
to sacrifice precision to rapidity, ease and cheapness. For 
these reasons the old and tried acid-bottle and similar fluid 
methods still hold the field in point of numbers, though 
the gyrocompass and multiple photographic methods 



vi PREFACE 

have entered the lists with the weapons of accuracy and 
certainty which alone can solve the problem satisfactorily. 
The history of our subject has not always escaped the 
stigma of charlatanry and perhaps it has often deserved 
it. With the growing application of established scientific 
principles and the subsequent checking and verification 
of these by other boreholes, shafts, etc., we may regard 
the day of skepticism as vanished. There is now arising 
an insistent and ever increasing desire for frankness, 
clarity and truth in borehole investigation which must one 
day achieve the universal respect accorded an exact 
science. Built on such foundations it is indeed difficult 
to imagine this ideal failing. 

M. H. Haddock. 

Leicester, England, 
Septe77iber, 1931, 




CONTENTS 

Page 

CHAPTER I 
Deviation and Its Causes 1 

CHAPTER II 
Auxiliary Registrations in Borehole Surveys. ... 22 

CHAPTER III 
Instrumental Survey of Boreholes 46 

CHAPTER IV 
Core Orientation 54 

CHAPTER V 
Fluid Methods of Surveying Boreholes. ...... 95 

CHAPTER VI 
Compass and Plumb-bob Methods 121 

CHAPTER VII 
Pendulum Methods 153 

CHAPTER VIII 
Photographic Methods 175 

CHAPTER IX 
Gyroscopic Compass Methods of Surveying Boreholes 204 

CHAPTER X 
Geophysical Methods of Investigating Boreholes . . 225 

CHAPTER XI 
Problems . 246 

CHAPTER XII 
Bibliography 281 

Index 291 

vii 



55525 



DEEP BOREHOLE SURVEYS 
AND PROBLEMS 

CHAPTER I 
DEVIATION AND ITS CAUSES 

The primary purpose of a borehole survey is to determine 
the extent of the borehole in length and deviation. The 
deviation is surveyed in angular deflection in amount and 
bearing; the amount relative to the intended initial direc- 
tion and the bearing with respect to the local meridian or 
any other fixed reference mark. 

In many boreholes frequently only the amount of deflec- 
tion suffices. Thus in exploratory borings in unknown 
measures the direction of deflection is of less value than the 
degree of deflection, owing to the remainder of the data 
being absent from our conclusions. However, for a correct 
decision respecting the strata penetraited, this knowledge 
is unconditionally necessary. 

Still more important are these determinations when 
the hole has to hold a pumping or bailing plant, as in certain 
petroleum borings. Here the longevity of the borehole is 
in considerable degree influenced by any noteworthy devia- 
tion from the plumb. Rods, or the bailing rope, con- 
tinually chafe in the same part of the casing; in a short 
time it becomes seriously injured. That all deep boreholes 
deviate — and by deep boreholes we imply all those over 
1,000 ft. in extent — is established beyond any doubt, and 
indeed much shallower boreholes deviate in more or less 
degree. 

Dr. Otto Stiitzer of Kiel has recently cited a case^ where 
two boreholes in the Moreni oil field of Rumania, com- 

1 Z. deut. geol. Ges., Bd. 81, Heft 10, p. 536 1929. 

1 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



menced vertically and at a distance of 60 m. apart, actually 
met at a depth of 850 m. 

About 25 years ago interest in the survey of boreholes 
was quickened by a series of very ingenious contrivances 
which were invented to cope with borehole deviation. 
Borings hitherto considered vertical were now subject to 
doubts. In 1908 Joseph Kitchen presented the results 
of his surveys of some 22 deep boreholes on the Rand 
before the Institution of Mining and Metallurgy^ which 
stimulated a wide discussion and was supported by many 
other instances of deflection. He surveyed the dip of the 
holes at intervals of about 500 ft. and averaged his results, 
which method, though not precise, sufficed as an indication 
of the great deviation in this area. With an average total 
borehole depth of 3,370 ft. he found an average horizontal 
displacement of 1,165 ft. with an average lowest depth of 
survey points of 3,015 ft. He shows in Table I figures of 
average angular deviations obtained by instrumental 
survey in the holes. 



Table I.— 


Average Angular Deviation in 


Rand Boreholes^ 




Nos. 


Nos. 


Nos. 


Nos. 


Nos. 


Depth, feet 


1 to 8, 


9 to 16, 


1 to 16, 


17 to 22, 


1 to 22, 




degrees 


degrees 


degrees 


degrees 


degrees 


500 


4.7 


2.5 


3.6 


8.8 


5.0 


1,000 


10.6 


9.2 


9.9 


15.6 


11.4 


1,500 


20.2 


19.7 


19.9 


20.2 


20.0 


2,000 


24.9 


27.8 


26.4 


25.4 


26.1 


2,500 


27.3 


30.1 


28.7 






3,000 


32.9 


34.4 


33.6 






3,500 


42.5 










4,000 


47.7 











1 After J. Kitchen by permission of the Institution of Mining and Metallurgy. 

These tend to oppose the general rule that inclined strata 
exaggerate the deviation which, however, may be a local 
circumstance. The accompanying displacement is shown 
in Table II. 

1 The Deviation of Rand Boreholes from the Vertical, by Joseph Kitchen, 
Session 1907-1908. 



DEVIATION AND ITS CAUSES 3 

Table II. — Average Horizontal Displacement in Rand Boreholes 





Nos. 


Nos. 


Nos. 


Nos. 


Nos. 


Depth, feet 


1 to 8, 


9 to 16, 


1 to 16, 


17 to 22, 


1 to 22, 




feet 


feet 


feet 


feet 


feet 


500 


15 


10 


10 


35 


20 


1,000 


85 


70 


75 


145 


95 


1,500 


210 


190 


200 


290 


225 


2,000 


400 


390 


395 


485 


420 


2,500 


610 


635 


625 






3,000 


860 


910 


885 






3,500 


1,150 










4,000 


1,485 












Fig. 1. — Sketch showing curves of boreholes and amount of horizontal displace- 
ment at various depths, (a) Vertical projection. (6) Horizontal projection. 
(After Joseph Kitchen.) 

The displacement is thus in these cases proportional to 
the square of the borehole length and it usually tends to 
describe a right-handed or clockwise curve. In one case 
the displacement was 2,573 ft. away in a borehole depth 
of 4,419 ft., i.e., a vertical depth of 3,288 ft. Mr. Kitchen 



4 DEEP BOREHOLE SURVEYS AND PROBLEMS 

grouped his results graphically about the same vertical, 
giving the remarkable suite of horizontal displacements 
shown in Fig. la and the accompanying angular deviations 
shown in plan in Fig. lb. 

All other influences considered equal, the amount of 
deviation depends a great deal on the method of boring. 
Many are of the opinion that the greatest deviation is 
obtained in the rotary system yielding cores as in the shot, 
calyx or diamond processes, and the least in the percussion 
systems particularly the free-fall systems. In a recent^ 
statistical survey of results which appear to support this 
contention the data yielded from 21 boreholes was as 
follows : 



Table III. — Summary of Some Rumanian and Russian Boreholes 
Using Different Methods 



Method of boring 



Number 

of 
boreholes 



Depth, 
meters 



Most 

favorable 

case 



Worst 
case 



Remarks 



Turbine borer 

(Kapeljuschnikov) 

Rotary system 

Rod percussive 

Rope percussive 

American rotary 

American-Chield rotary 



4 
4 

1 

1 

10 



580 
578 
840 
822 
480 
606 
580 
700 
595 



1° 


20' 


4° 


30' 


1° 


20' 


3° 


10' 


9° 


20' 



5° 10' 





" 


2° 


55' 

> 


11° 


0' , 


i 


25° 


0' 



In the 
same 
strata 

In the 
same 
strata 



However, this point is very debatable. The diamond- 
drillers claim that diamond-drilled holes can not drift as 
much as holes drilled by other methods because the core 
barrel nearly fills the hole. In hard rock the core barrel 
normally occupies all but Ke in- of the diameter of the 
hole. 

The rotary drill prevents the hole from drifting as much 
as would occur by other methods by using at the bottom 
a long steel drill collar of a diameter nearly equal to that 

. ^A. L. Schachnazarov, Engineer "Asnef" Oil Trust, Baku, in Petroleum, 
No. 23, p. 772. 



DEVIATION AND ITS CAUSES 



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6 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



of the hole.^ On the other hand, percussive borers claim 
that curvature is more easily detected and rectified by a 
reciprocating action especially by a free-falling tool.^ 

With regard to rotary boreholes a perusal of Table IV 
will well repay the reader. The table is taken from a 
compilation^ covering 255 California boreholes bored by 
the rotary system. The total depth was 1,158,542 ft. 
and the total number of measurements 13,150. As addi- 
tional proof of this almost universal deviation of deep holes 
we may cite the recent researches of D. R. Snow and H. B. 
Goodrich^ carried out upon some 90 wells in the Seminole 
oil field of America. These holes have been drilled since 
1927 and show the data collected in Table V. 



Table V. — Summary of Results of 90 Oil Wells 
{After Snoiv) 



Number of wells 


Vertical 
correction, feet 


Percentage of 
total wells 
surveyed 


Maximum 

possible 

horizontal 

drift, 4,500 ft. 


20 

9 

28 

24 

4 

5 

90 


Less than 25 
From 25 to 50 
From 50 to 100 
From 100 to 200 
From 200 to 300 
Over 300 


22.22 
10.00 
31.11 
26.67 
4.44 
5.56 


474 

669 

943 

1,327 

1,615 



Total surveyed: 377,719 ft. 

Total vertical correction: 9,290 ft. (per well, 103 ft.). 

Average angle of deflection: 12 deg. 44 min. 

In some relatively shallow boreholes, as in the concentric 
circumferential suites of boreholes preliminary to sinking 
shafts by the freezing process or by cementation, extreme 
accuracy of data respecting the course of the holes is of 

1 Diamond Drilling, U. S. Dept. Commerce, Bur. Mines, Bull. 243, p. 60. 

2 Cf. Organ des Verein der Bohrtechniker, No. 23, p. 279, 1910. 

^ A. Anderson of Fullerton, California, in Oil Weekly, October, 1929. 
*See also Oil Gas Jour n., p. 32, Mar. 14, 1929, and p. 218, Apr. 4, 1929. 



DEVIATION AND ITS CAUSES 7 

great importance. It is here that we find the greatest 
advancement in the technique of borehole-survey apparatus. 
This is significant not only because the proximity of other 
boreholes greatly increases the possibility of deflection 
but ignorance of the actual courses of the holes here would 
give rise to great trouble and expense later on; and perhaps 




Fig. 2. — Course of a full suite of boreholes for a freezing shaft (depths in meters) . 



disaster when encountering the unsolidified gaps between 
widely isolated frost walls or cementation zones. These 
possibilities will be apparent from a perusal of Fig. 2, 
which is an actual survey of the course of such holes previous 
to sinking operations. 

As the shallower seams and veins are won in the world's 
mineral fields it is manifest that deep prospecting holes to 



8 DEEP BOREHOLE SURVEYS AND PROBLEMS 

fresh deposits will become more common. In these daily- 
growing cases, especially in those situated near property 
boundaries, legal disputes will be settled by the results of 
borehole surveys. Again the deep borehole being the most 
straightforward and direct verification for any completed 
geophysical survey, any doubt which may arise as to (1) 
mapped lenses being missed in the borings, (2) the nature 
of the body surveyed aboveground (3) its extent, etc., can 
only be verified by a thorough instrumental survey of the 
boreholes concerned. Since deviation of a string of tools 
may take place in the ultimate up to and beyond 60 deg. 
from the originally intended direction,^ and boreholes are 
now attempting the enormous depth of 10,000 ft. and more, 
the great significance of deflection surveys is obvious. 

Horizontal and inclined boreholes, particularly upward 
inclined holes, deviate sooner and to greater extent than 
vertical ones.^ They also give rise to a special set of 
deflection apparatus, but, generally speaking, results of 
surveys of such holes are not so reliable as those of vertical 
ones. Thus most of our remarks will apply to deep vertical 
boreholes. 

There is no doubt that the best evidence of initial or 
subsequent deflection in boreholes is to be obtained from 
the precision with which the working of the entire system 
of boring is checked. The onus rests almost entirely upon 
the boring master and personnel, chiefly because the site 
is usually situated far from the headquarters of the boring 
company and its direct command. Thus the master borer 
should be selected mainly on his experience, skill and 
ability, other qualifications notwithstanding. There is 
more responsibility upon him than in any other sphere of 
technical work. This applies more in foreign and remote 
lands. Thus it is important that all hands graduate in 
the actual school of practice from the meanest position 
upward. 

^ Kitchen, op. cit., mentions one deflection of 66 deg. 
^ Justice, J. N., Channing, Park, Trans. Inst. Min. and Met., Vol. 12, 
p. 319; Proc. Lake Superior Min. Inst., Vol. 2, p. 23, 1894. 



DEVIATION AND ITS CAUSES 9 

The modern tendency to standardized reserve parts 
and processes, also the recent step toward normahzing 
as many of the movable or removable parts as possible will 
tend to unify knowledge of and the results of deflection. 
It will tend toward closer correlation of data and more 
exact anticipation of deviation and therefore more successful 
handling of the problem when it arrives. 

This will be aided by duplicating staffs too, such as 
smiths and fitters in diamond boring and tool dressers in 
chisel boring. They must always have a clear rinsing 
circuit with the borehole base, especially in rapid-stroke 
boring as by the Raky method. They will need exceptional 
skill in rope boring. 

Another essential adjunct to the detection and elimina- 
tion of curvature lies in the supervision of the water circuit 
by the master borer and the leading hand and by maintain- 
ing a keen supervision for traces of oil or minerals. This is 
closely connected with the amount of water struck in the 
borehole, the pressure on the rinsing pumps, etc., so that 
they may have to decide upon the cutting off of water 
according to the strata pierced or its increase under certain 
conditions; or even decide to change the type of borer. 
In their responsible positions as borehole casers and core 
extractors much will be learned respecting deflection which 
can scarcely be described in writing. 

The best aid to all of these observations will be found in 
a thoroughly checked and entered log of progress, a study 
of which will assist very materially in reading any progress 
graph which may be attached in the derrick house. These 
provide pictorial and descriptive checks on the tendencies 
to deviate and often their causes. Strata profiles and 
sections should be kept as well as vertical sections. Finally 
the care of the actual samples, or cores, is absolutely essen- 
tial as the final check on any adduced ideas as to deviation, 
etc. It will be seen that the requirements demanded 
of a good master borer are so exacting and varied that the 
systematic training of such a person is a really essential 



10 DEEP BOREHOLE SURVEYS AND PROBLEMS 

need. Unfortunately, apart from Rumania, there are no 
actual master borers' schools in Europe. 

The Detection of Incipient Curvature in Boreholes. — 
Suspected curvature of the rods may be checked by noting 
the following surface indications of the deflection. It must 
be noted that these indications may be entirely absent, 
making the curvature untraceable without instrumental 
means. 

a. The uneven wearing of the chisel or crown hit due to 
encountering unequal resistances at the floor of the hole. 
The contact surface of the tool tends to become inclined due 
to excessive wear on one side. It also tends to snap off. 

6, Lateral abrasions of the rods and brushing of the rope 
sides in rope boring. This is due to side wear and in the 
case of rigid rods will usually show the side on which curva- 
ture is occurring, i.e., the ''off" side. 

c. Difficulty in Inserting the Casing. — Frequently the 
casing sticks fast as often does the boring tool owing to the 
curvature. 

d. Scoring of the core and core box in rotary boring. This 
will often provide fair information as to the cause of the 
deflection. 

e. Laboring of the Rig Gear. — The surface engine labors 
under the extra load, the bearings run hot and general signs 
of lack of uniformity ensue. 

/. Study of the Progress Reports. — This often provides 
clues which can be reduced to curvature as the cause of 
variations in the progress graph. 

g. Throttling of the circulating water, the circuit being 
accomplished in gusts and frequently hindering or loading 
the plant. Lesser deflections may be corrected by second- 
ary boring or partial reaming. The borehole will thus be 
widened and the casing set without being influenced by 
the previous borehole walls. This simple remedy only 
applies to deflection which has been detected just after it 
has begun. 

h. Instrumental Means. The Anschiltz-Kaempfe Acoustic 
Device. — Nearly all of the many and varied devices for 



DEVIATION AND ITS CAUSES 11 

surveying boreholes and many of those appUed in core 
orientation may be used for detecting initial curvature or 
deviation. However, most of these are only suited to 
separate application, very few of them being fitted for 
employment during actual boring operations especially with 
percussive boring systems. The difficulty has been well 
solved by the device of Dr. Hermann Anschiitz-Kaempfe 
of Kiel which provides an acoustic or audible warning 
of the initial stages of deflection. He invented this 
apparatus in 1915 and improved on it a few years later. 
It applies particularly to percussive boring but may be 
modified for rotary boring. It is essentially a means of 
detecting deviation, measuring it, and later correcting it. 
It has been applied successfully in both Europe and 
America. The apparatus as applied in borehole surveys 
is shown in Plate I, Figs. 1 to 5. 

Figure 1 (Plate I) is a vertical section of the boring 
chisel bar and bit. Figures 2 and 3 are enlarged views of 
this section at an angle of 90 deg. to each other, while Fig. 
4 shows the electric drive circuit. The hollow bit holder a 
holds the beveled bit ai below and the connection a2 above 
to the rods, the dotted lines xx being the normal flushing 
circuit. A closed outer casing tube as mounted in the hollow 
bit holder a holds the transmitter and the inner casing tube 
ai which is longitudinally adjustable in this by means of 
buffer springs h and 6i and held by lugs c. An accumulator 
battery with electric motor d in the transmitter drives a 
worm di with its wheel d2 on support ds and thus the toothed 
wheels d^. Four pins e about the worm wheel d2 engage 
consecutively on rotation with the finger / of hammer /i 
controlled by pressure spring g. Thus for each revolution 
of wheel c^2 four blows of the hammer /i are produced at /a. 
Toothed wheel d^ engages another toothed wheel h on shaft 
hi and carries a screw thread barrel hi which can be dis- 
connected by spring slides i, ii and i^. There is an electric 
contact A' on slide i. 

The ball and socket end I of the barrel shaft hi allows it 
to oscillate under the adjustable spring pressure pin m 



12 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



.-ci^ 




Plate I. — The Ansehiitz-Kaempfe deviation detector. 



DEVIATION AND ITS CAUSES 13 

and nil held by springs n and Ui and plungers ^2 and Uz 
in cylinder o. Rod mi passes up into a hollow space in 
plunger ^2 so that when the pressure of spring n acts, pres- 
sing plunger n2 downward, rod mi passes into the space in 
nz. This space has a check-valve controlled upper end p, 
which opens when the plunger ^2 descends and closes when 
it ascends, equilibrium of pressure being effected by a fine 
bore pi. The brackets q carry an electrical contact r 
which is closed when plunger 712 is in its upper position 
(Fig. 2) and broken when this descends. 

The lugs s hold the heavy pendulum t in a frame and the 
swing of t into casing a^ is arrested by a stop u and in 
the other direction by a stop Ui. This pendulum carries 
a second part of the contact k of slide i so that the positions 
of the pendulum t and slide i decide whether the contact 
k is opened or closed. The two electric contacts k and r 
are arranged in the circuit from the source of power d, 
which operates worm di. These two contacts (Fig. 4) 
are arranged in series so that the motor is stopped if only 
one is switched out. This occurs as follows: The plunger 
712 continues its descent by momentum after the boring 
tool has struck its blow, and this compresses the adjusted 
springs n and Ui, thus turning the screw spindle hi and disen- 
gaging it from the half nut h2 so preventing slide i from 
moving. But contact r is now broken, stopping motor 
d and screw spindle hi. Plunger n2 can only move back 
upward slowly, owing to the design of air valve p and the 
hollow space nz, and this is designed so that before the spin- 
dle can return to its working position and r close a new 
blow — assuming regular working — with a downward move- 
ment of the plunger takes place. In interrupted working, 
say over 20 sec. between blows which is a maximum time 
for springs n and rii, the mass of plunger no and the valve p 
function ; 712 returns to its initial position, throws in spindle 
hi and closes the r contact. This starts motor d if contact 
k is also closed. The closure depends on the position of the 
pendulum t, for when we have deviation of the bit to the left 
throwing t to the right, or engaging it with stop Ui, contact 



14 DEEP BOREHOLE SURVEYS AND PROBLEMS 

k is open and the motor with its connections stops. If, 
on the other hand, the bit holder has deviated to the right 
(Fig. 5) the working circuit is closed, the motor actuating 
worm di. Now worm wheel di with pins e engages hammer 
/i to strike the wall of casing a^ as each pin passes lug /. 
These blows on the casing are clearly perceived at the sur- 
face and counted by means of a listening earpiece on the 
rods or any simpler device. 

At the same time as worm wheel d2 starts, the screw spin- 
dle hi moves slide i to the left in opposition to the action of 
spring i2. The pendulum contacting on the slide follows 
this motion until it hangs free, breaking contact k and 
stopping motor d. Until this happens we get four hammer 
blows per revolution of worm wheel di, so the observed 
total number of blows indicates to what extent slide i 
has moved to the left in order that pendulum t hangs free 
and vertical; that is to say, it is a measure of the deviation 
of the bit holder and bit. 

The surface observer has now only to stop the boring 
blows from time to time and listen to the blows of hammer /i 
against the boring rods in order to ascertain the extent of 
the deviation. 

Turning the chisel 90 deg. gives the inclination compo- 
nent in the plane of the reader's vision as against that of the 
drawing and where the component is greatest is the direc- 
tion of maximum inclination. Otherwise two independent 
pendulums in planes at 90 deg. to one another can be used. 
Having got this line of major inclination the deep edge of 
the beveled chisel is turned to deal with it and correct the 
deviation. 

Though the device gives only the inclination component 
relative to the chisel and not to the geographical position 
of the borehole, twisting of the rods need not be heeded so 
long as the transmitter does not twist relative to the 
chisel. 

In this way incipient or initial deviations can be quickly 
detected and corrected. The device can, with suitable 
modification, be applied to rotary boring and it can also 



DEVIATION AND ITS CAUSES 15 

be employed apart from the bit holder as a plumbing 
apparatus, the principle of acoustic signals being preserved. 

However, in spite of all precautions we cannot always 
note at once a big and gradual curvature at its commence- 
ment from the above observations alone. The detection 
of a suspected curvature being essentially a surface task 
in the initial stages of deflection, the next procedure is to 
investigate the causes previous to checking the amount 
and direction of the deflection. The causes are numerous 
and often local, and in many cases are due to faulty surface 
conditions. 

The Causes of Borehole Deviation. — a. Incorrect Center- 
ing at Surface. — This, though sometimes tending to right 
itself in such methods as the free-fall system, of course soon 
leads to heavy deflections. 

b. Alternating hardnesses of successive layers of hard and 
soft rock. Inexpert handling of the drill feed whether 
by the multiple gear or hydraulic feed here tends to cause 
racing in the shaly and soft beds and laboring in the harder 
strata. The tool tends to supplement this by following 
the softer stratum unless fed or geared to meet the circum- 
stances.^ In such cases boring has to be undertaken very 
carefully and frequent patroning, or damming and reguid- 
ing, has to be resorted to, thus removing immediately the 
slightest deviation from the plumb. 

Table VI. — Moh's Scale of Hardness 



No. 


Mineral 


Relative hardness 


1 
2 
3 

4 


Talc 

Rock salt 

Calc-spar 

Fluor spar 1 


Easily scratched with the finger nail 
Not easily scratched with the finger nail 
Easily scratched with a knife 

Not easily scratched with a knife 


5 
6 


Apatite J 

Felspar 


Difficult to scratch with a knife 


7 
8 


Quartz ] 

Topaz 

^ ^,. > 


Cannot be scratched with a knife 


9 
10 


Sapphire 
Diamond 





1 See also Hugh F. Marriott, discussion to Deviation of Rand Boreholes, 
etc., p. 115. 



16 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



Thus if any mineral above be used in the form of a sharp 
point it will scratch the preceding members of the series, 
e.g., should we find a piece of mineral which will scratch 
calcite but not fluorite its hardness is between 3 and 4, 
say about 3^2- 

Table VII. — Hardness of Some Common Minerals 



Mineral 



Hardness 



Asphalt 

Augite 

Barites 

Bournonite 

Brown haematite 

Calamine 

Cassiterite 

Cerussite 

Chromite 

Copper glance. . . 

Corundum 

Felspars 

Graphite 

Gypsum 

Haematite 

Hornblende 

Ilmenite 

Magnetite 

Malachite 

Micas 

Mispickel 

Native copper. . . 

Ozokerite 

Pyrolusite 

Quartz 

Salt 

Silver glance .... 

Soda niter 

Spathic ore 

Stibnite 

Sulphur 

Tourmaline 

Wolfram 

Zinc blende 

Coals : 

Anthracite .... 

Bituminous. . . 

Lignite 



1.5 

5.5 

2.5 

2.25 

4.25 

5 

6.5 

3.25 

5.5 

2.25 

9 

6.5 

1.5 

1.25 

5.5 

5.5 

5.5 

5.5 

3.25 

2.5 

5.5 

2.25 

0.75 

2.5 

7 

2.5 

2.25 

1.25 

3.5 

2 

1.55 

7.25 

5.25 

3.25 

2.25 

1.25 

.5 



Remarks on cores 



Melts at about 100°C. 



Brittle 
Lenticular fracture 



Sometimes magnetic 



Splits easily 
Cleaves readily 



Sometimes magnetic 
Very magnetic 

Cleaves easily 



Melts at about 60°C. 

Cleaveless 
Dissolves in water 
Breaks in slices 
Dissolves in water 
Nodular 

Sometimes flaky 
Brittle 
Fractures easily 



Brittle, shelly fracture 
Brittle, cubic fracture 
Friable and platy 



DEVIATION AND ITS CAUSES 17 

The hardness of minerals is fairly constant but of rocks 
this is not the case. This is due to the fact that minerals 
have a more definite and rigid chemical constitution than 
rocks, since the latter are aggregations of minerals. The 
minerals in rocks being in any proportions between certain 
arbitrary limits the hardness of a particular rock varies with 
its type, i.e., the percentage of its dominant mineral. 

c. Inclined strata especially rapid changes in the inclina- 
tion as in boring through sharp unconformities, domes, 
folds and thrusts. The tool tends to follow the dip at 
the contact. (However, this is not a rigid statement.)^ 
If we are dealing with the percussive system we must bore 
with short strokes so that the cutting tool meets a cleaner 
face since the rinsing water can better deal with the debris. 
With no rinsing system the hole must be sludge pumped 
often so that the direction of impact is in the prolonged 
line of the rods. If this is not done the chisel will nurse 
the dip. In the rotary system of boring these difficulties 
are often almost insurmountable. 

Other geological causes of deviation of a drill hole may 
be: 

1. Bowlders, concretions and dykes. 

2. Faults, thrusts and unconformities. 

3. Caving and movement of strata in the uncased part 
of the hole. 

4. General earth movement. 

d. Lack of Rigidity in the Rods. — Even in the tightest 
joints the slightest joint play will initiate curvature with 
straight rods, just as railway curves can be made entirely 
of straight rails. 

e. The Proximity of Other Boreholes. — In boring by 
percussive methods, for instance in the freezing process 
for shafts, the ground is disturbed by the continual shock 
of the tool so that new holes put down near by tend to 
deviate into the zone of least resistance. Again any iron 
such as parts of old tools or casing in the old hole will 
accentuate the deflection. This of course applies also 

^ Kitchen, op. cit., p. 100. 



18 DEEP BOREHOLE SURVEYS AND PROBLEMS 

to new holes near those old holes which have been shattered 
at their base by time charges to increase the yields as was 
first done in the Pennsylvania oil field. 

/, Fissured Strata.'^ — These may direct a borehole in any 
direction. 

g. Pressure on the Rods. — In many boreholes, particularly 
in diamond drilling, the tool tends to turn against the dip 
of the strata and this is greatly affected in the case of a 
hole nearly meeting the strata plane, i.e., nearly flat strata 
in vertical holes; that is to say, ''face on" in inclined holes. 
Hydraulically fed drills in these cases are best, like the 
Sullivan, which control the rod pressure and adapt it to 
keep the crown pressure constant. Thus in soft strata 
the water escape in the hydraulic cylinder being more 
rapid the drill descends more quickly and vice versa in hard 
strata. On the other hand, screw feed drill speeds are set 
between fixed limits regardless of petrologic changes in the 
hole. In harder strata greater pressure on the rods tends 
to produce a screwlike action. 

h. Reduction of Borehole Diameter. — The necessary peri- 
odical changes in diameter to lessen the weight on the engine 
and crown no doubt affect the plumbness of the hole. 
The upper parts of the hole being wider allow the rods 
more latitude, and the rods tend to curve by displacing 
the center of the crown bit from the hole center. Alterna- 
tions in hardness supplement this eccentricity. Longer 
core barrels up to 50 ft. have in places been adopted to 
ameliorate this tendency. 

i. Oversetting the Diamonds in the Crown. — It is considered 
good practice to set the diamonds so that the hole is about 
Ke in. more in diameter than the core barrel; i.e., M2-in. 
projection for the diamonds over the crown. 

Any greater overset makes too much play between the 
core barrel and hole or between drill rods and hole so tending 
to set up lateral movement. 

j. Weak Core Barrels and Small Holes. — Weakness of the 
barrel especially at the crown screw tends to twist the tool 

1 Dickinson, Joseph, F. G. S., Trans. Inst. Min. Eng., Vol. 35, p. 397. 



DEVIATION AND ITS CAUSES 19 

and in turn the hole. Thus long barrels are often faulty 
for want of strength and undue pressure on the crown. 
There appears to be much in favor of bigger holes and 
reduction not proceeding beyond l^i in. at 2,000 ft. Weak 
barrels may cause screw deflection. The crown often 
returns to its original direction after deflection has occurred 
in some West Australian borings. With big rod reductions 
the play cannot be entirely eliminated at the step joint. 

k. Static Electricity and Magnetism of Rods. — This effect 
due to frictional abrasion is often very pronounced and 
can be demonstrated by means of a poker of soft iron, a 
hammer and compass. It must, if of definite persistent 
polarity, tend to deviate the rods toward the pole sought.^ 
Magnetism will tend to arise also from brushing with casing 
and the strata if heavily iron borne as in the basic igneous 
rocks. Some further notion of the causes of borehole 
deviation may be obtained by considering the eventualities 
inherent in all boreholes, as yet beyond human control, 
as are evidenced in any attempt to fix the dip of strata abso- 
lutely from observation on a given core. 

Only approximately can we obtain the dip angle of strata 
bored through by considering the core features alone. 
This is very simple but the estimating of the direction of the 
dip and thence the strike of the beds in such a case cannot 
be done without some form of stratameter which gives 
the dip and strike accurately from the data presented. 
The objection here is that the observation is too local and 
the data too scanty. We have to assume that the core 
yielding the data has been accurately gripped by the core 
catcher. Thus in the surface check on the core no account 
has been taken of the turn of the rods on tearing off the core 
previous to extraction. An American method of partially 
avoiding this is to score a continuous line down the rods 
after tightening with special joints and then check the dip 
shown against this line of known azimuth. Now the 
longer the line of rods and tools the less can they be regarded 

^ Jennings, J., Jour. S. African Assoc. Eng., Vol. 12, p. 7, 1906; Cooke, 
L. H., Trans. Inst. Min. and Met., Seventeenth Session, p. 126, 1907. 



20 DEEP BOREHOLE SURVEYS AND PROBLEMS 

as a rigid rod because under the influence of their growing 
proper weight, rending, shear and turning forces arise which 
cannot be checked aboveground. Unfortunately, regard- 
less of any errors of observation or measurement at the sur- 
face, the circumstances attending the wrenching off 
of the core and the working of the rods influence the deduc- 
tions very greatly. In solid strata the core is wrenched off 
by a sharp jolt, otherwise we cannot tell whether the core 
and strata are in their proper natural relation as before 
rupture. In friable strata the core is frequently released 
during boring operations due to the successive boring 
shocks, and this also occurs frequently in rigid strata where 
we have intercalated beds of clayey and shaly rocks. 
Furthermore, the instant of jar for tearing off the core 
often witnesses a slight rotation of the rods. The lower 
surface of each core section should exhibit no traces of 
shear horizontally; the fracture should be clean, for then 
we can feel more secure that the small wrench twist is 
absent. In order to ensure that the twist is eliminated or 
minimized, the rod should be raised a little off the hole 
base before the fangs of the core catcher come into action. 
This gives the grip a better chance of making an accurate 
engagement, because the spin of the string of tools has 
abated. This spin definitely affects the direction of bore- 
holes. The catcher now brought into action, a sharp 
upward thrust will stand a better chance of yielding a core 
with the conditions between core and strata preserved as 
before rupture. No change from this position must occur 
during extraction of the rods. The rod marks must be 
carefully watched and bumping of the string of tools 
on the borehole walls prevented. There should be no traces 
of turning at the core grips. 

These conditions are so rigorous and so difficult of 
application and the circumstances attending the wrenching 
off of the core are so utterly beyond entire control that 
absolutely exact results can not be hoped for from one core 
alone. With cores of small diameter the small wrench twist 
gives an error of several degrees and the smaller the diam- 



DEVIATION AND ITS CAUSES 21 

eter the greater the error; furthermore the smaller the diam- 
eter the greater the lack of control in extraction or boring, 
hence the greater tendency to deviate. The best dip 
and strike data are to be obtained from computations 
on depths yielded by three or more boreholes not in the same 
straight line. 



CHAPTER II 

AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 

Previous to discussing the various instrumental methods 
of surveying deep boreholes some of the more important 
ancillary records kept on modern plants will be described. 
These additional memoranda aid very materially in check- 
ing the accumulated borehole data in that they frequently 
save much time and guesswork as to causes of various 
curious features incident to deep boring. 

PROGRESS RECORDS 

These are continuous automatic checks or descriptive 
graphs of the progress of the borehole in respect to length 
and time. They provide a check on the difficult and 
often unreliable observations of the boring personnel. 
They yield conclusions as to the successive hardnesses 
of the strata pierced and assist in their determination, 
since each stratum corresponds to a definite boring pace. 

The simplest device is a scale fixed on the rods and read 
every 5 min. and booked, but it is more exact to have a 
record depending on the length of hole and revolutions per 
minute, since the rapidity of boring through strata depends 
on the r.p.m. of the rods in the rotary or the number 
of strokes per minute in the percussive system. They are 
known as stratigraphs or strata-progress recorders. 

Jahr's stratigraph^ (Fig. 3) consists of a pen recording 
on a graph drum the latter revolving at the same rate as 
the rods and its motion round being at right angles to that 
of the pen. Thus the increase of depth of the crown bit 
will appear as abscissae and the corresponding revolutions 
as ordinates. The recorded line is thus the steeper the 

^ E. Jahr, Chief Mine Survej'or, Breslau. 

22 



AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 23 



faster the boring progresses and the flatter the slower the 
crown penetrates the measures; therefore a horizontal 
portion of the line shows that the tool is not piercing the 
rocks even though the rods are rotating; that is to say, 
that the rod feed is not paying out. When the plant is 



S^^m%^ Y/////?///^/y//////i^/^^///'//^, 




Fig. 3. — Jahr's stratigraph — the derrick drive. 

idle, and therefore the driving shaft of the recorder, the 
registration ceases. The most important inferences from 
the record are provided by changes of direction in the pen 
line because they show that different strata have been 
struck and thus provide valuable clues as to the conditions 
arising in this new ground. Such a change in the line only 
occurs in the flatter measures ; in inchned deposits the change 
is more gradual because the crown only then penetrates 
the new stratum gradually. In Fig. 3 note that the motion 



24 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



of the graph paper n is caused by the sinking of the rods a. 
A hook e on a ring on the boring spindle catches in the chain. 
This chain runs over the rollers g, gi and g2 and is kept 
taut by the weight h. The motion of the roller g is trans- 
mitted by means of a bevel wheel on the shaft I so that the 
paper moves corresponding to the deepening of the borehole. 
The speed of the paper depends on the transmission between 
the bevel wheels i and k. The pen moves on an endless 
chain p (Fig. 4) at right angles to the direction of the drum 
graph, and it is driven by the toothed wheels q and q^. 




iJL^ M fiS, 




i 



1 



Fig. 4. 



Fig. 4a. 



Fig. 4. — Jahr's stratigraph — the recorder. 

Fig. 4a. — Showing relation of record to measures for estimating depth 
thickness of beds. 



and 



The chain is driven by belting r from the driving shaft 
of the engine *S. The recorder has several pens m^, m^, 
etc., spaced on the chain p at vertical distances equal 
to the depth of the record paper. Whenever a pen reaches 
the top edge of the paper it leaves it just as the next lower 
pen comes into action to continue the record, since their 
distances apart equal the depth of the graph paper. Thus 
the record is got as a continuous series of broken lines 
which can be cut and arranged later if desired. 

It will be seen that the quicker the boring rods sink the 
more the curve will approach the abscissa direction and 
there will be a change in the curve for every different speed 



AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 25 

of sinking. On the upper edge of the paper (Fig. 4), a 
curve scale can be fixed for the continuous series of borehole 
depths, which can be diminished to a definite scale by means 
of suitable transmission bevels i and k. Thus, given 
favorable conditions, we may obtain the approximate 
dip of the strata by noting the length of the transition 
in the curve between two changes in it. Note in Fig, 
4a, which shows the progress of a diamond-drill borehole, 
that the curve is uniform to a as the crown is cutting in 
clay shales; from a onward, where the crown encounters 
the milder strata (coal) the curve flattens, and from h to 
c where it is entirely in coal it flattens more, steepening 
again at c on passing through the softer coal into more hard 
shale. An enlarged view of the borehole is shown in Fig. 
4a to assist in elucidating the problems arising. Thus 
bd is the borehole diameter and ab the depth difference 
read on the curve scale, hence the strata dip 

tan a = ^ (1) 

from which the actual thickness eg is easily obtained, since 
thickness of strata = ac cos a. 

To facilitate reading, the depth of each change of strata 
may be marked on the record. If necessary the recorder 
can be driven independent of the plant. This method 
has been well tried with good results at one of the deepest 
boreholes in Germany, at Czuchow in Upper Silesia. Still 
it is only an aid to recording strata and is not infallible 
especially in very varied thin alternations of highly inclined 
beds. Better results would arise if the paper were made to 
move corresponding to the strata dips. Jahr's method 
may, however, be regarded as a valuable adjunct to boring. 

Lapp's Stratigraph. — Here the pen moves by clockwork 
at a definite rate over the paper which moves corresponding 
to the deepening of the borehole. The recorder is connected 
to the rope drum shaft on the pay-out feed from which 
the rods hang. In Fig, 5 we have a view of Lapp's device 
in which the worm wheel s transmits its motion through a 



26 DEEP BOREHOLE SURVEYS AND PROBLEMS 

chain on to the scroll paper winding on a shaft. As 
soon as the feed apparatus turns backward, e.g., on dropping 
into the borehole, the paper roll is automatically cut out; 
the pen then indicates a straight line across, as when the 
plant is at rest. The pen works by clockwork and in one 
hour moves over the breadth of the paper and after auto- 
matic reversal works back in the next hour. Thus the 
record is a continuous zigzag line. The apparatus is 
enclosed in a glass-topped case which permits of a constant 




Fig. 5. — Lapp's stratigraph. 

observation of the progress of the borehole respecting the 
corresponding time. It does not cut out when the plant 
is idle as in the case of Jahr's device, and, since this latter 
is a check on the actual working time, it can be considered 
that Jahr's method is superior. But it can be applied 
to percussive boring since it works off the tool feed ; however 
this may be a source of uncertainty since the feed is here 
hand operated. Thus the record depends on the careful 
manipulation of the feed which if correct, i.e., if the record 
corresponds exactly to the progress of the hole, will give 
uniform results with Jahr's method. Both methods lack 
in that uniform rotation of the rods is not always obtained 
in practice. 

The Foraky Recorder. — This stratigraph is a clockwork 
device with paper roll and recording apparatus. The 



AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 27 

principle of recording the progress of the borehole is here 
again dependent on the sinking of the rods and time. 
The paper is turned by clockwork and the recording pen is 
driven by the feed device. The paper roll is chosen of 
such diameter that the clockwork rotates it on its axis once 
in 12 hr. and 1 mm. of paper corresponds to 1 min. of time. 
Therefore millimeter paper is chosen for the graph. The 




Fig. 6. — Foraky stratigraph. 

recording contrivance is driven from a screw spindle on 
the rod feed in such a way that a sinking of the rods of 10 
cm. corresponds to a progressive motion of the pen of 1 
cm. 

The inked pen C (Fig. 6) moves ^ proportionally with the 
descent of the rods. It is connected to the rods by the screw 
spindle d from the feed device and by a cone- wheel trans- 
mission gear e actuating the screw spindle /. This carries a 
positive nut g holding the pen c. The axis of the clockwork 
b gives the true reading and the whole is encased in the 
casing h for protection. The apparatus is placed on a frame 
in the boring tower but not in contact with it. It has been 
successfully applied to depths of over 4,000 ft. 

^Gluckauf, p. 417, Mar. 18, 1911. 



28 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



The results obtained are very satisfactory but the 
apparatus exhibits the same deficiencies as Lapp's appa- 
ratus because the basis of the record is time and not the 
revolutions of the rods, and here even in a higher degree. 
Since the motion of the recording surface is always uniform 
it turns too quickly in solid strata and too slowly in broken 
strata. In this way the variations in the recorded line, 
upon which the stratigraph depends as stated previously, 
are weakened, while in Lapp's method where the pen 
works by clockwork they are increased. The irregularities 
in the velocity of rotation of the rods in working are of no 
great importance since the expenditure of power for the 
proper action of the crown is small as compared with the 
movement of the rods. 

Depth Measurers. — There are many types of these, the 
simplest being the direct types. Figure 7 shows the simple 



. Measuring 
^ Wheel 




Frame 



Rone K>i 



Fig. 7.— Depth measurer. 

direct depth measurer of the Lucey Products Corporation 
of Tulsa, Oklahoma, known as the Thatcher Depth- 
ometer. It is easily assembled on a rod frame and is very 
portable, being only 15 to 16 lb. in weight and can be used 
on ropes up to Ij.^ in. diameter. The measuring wheel 
transmits its revolutions by toothed gearing for direct 
reading, and it can be used on bailing and apparatus lower- 
ing ropes as well; also it can be used when letting the rope 
into the hole or when pulling it out. 

Borehole Diameter Measurers. — Decisions as to the 
variations in the diameter of a borehole are often necessary 
to settle difficulties arising during boring. 



AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 29 

These difficulties may occur when 

1. Casing operations are obstructed. 

2. Cutting bits jam on extraction. 

3. Abrasion develops at localized places. 

4. Cushioning occurs on the percussion stroke, 

5. Water circulation is affected. 

6. Sludging, pumping, bailing and such operations are 
hindered. 

The action of these gages need not be intermittent, i.e., 
a continuous reading can be made for only one insertion 
of the apparatus. Former methods of laborious multiple 
readings are thus avoided. A borehole becomes restricted 
chiefly owing to the following causes: 

1. Inexpert tiller work on hand-turned drilling with a 
straight bit; cruciform or horseshoe bits are less likely to 
cause diameter restriction. 

2. Buckled casing due to joint or sheet rupture under 
internal pressure or external strata movement on weak 
casings. 

3. Earthquakes. 

4. Time charges at hole base. 

5. Curvature of the borehole and its causes. 

6. Uneven wear on the cutting tool not attended to in 
time.^ 

Rumpf and Kleinhenn's Apparatus. — This apparatus 
can also . be used for tubes and flues. The chief part 




Fig. 8. 



of the device (Fig. 8) consists of a system of calipers 
arranged to follow the inner walls of the borehole or casing, 
its movement being obtained as a magnified image either 
optically or mechanically inside the borehole, 

iWoTZASEK, F., Z. I.V.B., p. 178, June 20, 1928. 



30 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



Figure 8 shows a longitudinal section of the device 
placed in casing 6 being examined. It will be seen that the 
central body 1 of the apparatus closes the tubular wall 2 
into a chamber. About the central body 1 are the levers 
4 which turn on axes 3 and carry rolling calipers 5 following 
the borehole or casing walls. These levers 4 may have 
any suitable form in cross section, preferably a definite 
form at their ends 8, e.g., triangular, in order to get a sharp 
projection image which is thrown on the frosted glass 
10 by a dry-battery lamp 9. The levers press on the casing 
walls by the action of springs 7, pressing them against the 
central boss on the other side of the fulcrum axes. 




Fig. 9. 

Figure 9 shows another form of construction wherein the 
caliper system 5 and spring 7 are arranged in another order 
of leverage. In each case springs 11 also assist springs 7 
in centering the apparatus in the borehole or casing. A sim- 
ple removal device is a set of hooks 12 and draw cables 13 
uniting into a central cable. 



,1 


1 


.11 


.1 ,6 


5-. 




Y"""jL 


^g^— J'^T'^-: 




i3^ 


1-7 


v^~-v 


loj 

l] 






jHid 


\ 


t^ 9 



Fig. 10. 

Figure 10 shows the most recent form of the device 
produced in the laboratories of the Batavian Petroleum 
Company (Astra Romana). Here the displacement of 
the cahper system due to diameter variation is indicated 
optically in a magnified image. The caliper system 5 is 
here a piston system working in a cylindrical case and 
pressed on to the borehole or casing walls by springs 7. 
A source of light produces a magnified image on disc 10 



AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 31 

through a system of lenses 14. It is found advantageous 
for registering results to have a series of concentric circles 
on the frosted glass plate 10, each circle corresponding to a 
definite variation in the diameter of the borehole. A 
kinematographic registration also suits the apparatus well, 
in which case the hood 10 is completely replaced by a kine- 
matographic recording device. When employing the latter 
the motion of the apparatus down the hole must be uniform, 
so the survey film obtained will yield an exact image of the 
condition of the borehole or casing diameter. 

We will not deal with any of the old time-wasting and 
tedious methods of single observations and records. 

PRESSURE RECORDS 

It is well known that in horizontal and inclined boreholes 
the tendency to deviation is greater than in vertical ones^ 
Although this tendency is mostly downward with horizontal 
and upward with inclined holes, many holes, particu- 
larly in inclined measures, tend to deflect upward. ^ Alter- 
nating hardness, etc., also affects this. These deviations 
are accentuated by the action of gravity and lower side 
abrasion on the rods due to the weight of the crown. In 
the case of horizontal and well-inclined boreholes (from 
the vertical) maximum manometers are employed to 
register the water pressure in the hole. 

The "Burbach" Pressure Recorder. — Where the deflec- 
tion is downward, as in the usual cases, this method employs 
the principle of gaging the pressure of the rinsing water 
at various points in the borehole and contrasting these 
records with the conditions at the borehole mouth. Where 
the deflection is upward the pressure on the rinsing pump 
may be gaged. 

a. When the borehole deviates downward, a tube piece is 
screwed on to the boring rods. The apparatus of the 

1 Justice, J. N., Trans. Inst. Min. and Met., Vol. 12, p. 319; Kitchen, J., 
ibid., Seventeenth Session, 1907-1908. 

2 Janson, Proc, Vol. 11, p, 48; Lake Superior Min. Inst., Vol. 2, pp. 26-30, 
1894. 



32 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



Burbach Works, Beendorf, Germany, contains a manom- 
eter c with a bent measuring tube d (Fig. 11). The fluid 
enters through holes a from the borehole and holes h to 
the measuring chamber and gaging tube. The manometer 
is provided with an indicator which fixes the highest pres- 
sure. The measurements are very simple; the rods and 




Fig. 11. — Horizontal borehole pressure recorder. (Burbach.) 

gage are pushed into the hole to the spot to be measured, 
the hole being full of rinsing water. Then on pulling 
the gage out and reading the highest pressure thereon the 
deviation from the horizontal can be calculated by consider- 
ing the specific gravity of the rinsing fluid. This latter, 
of course, is essential since water is not the only fluid; in 
potash mines magnesium chloride liquor is used. 



Borehole set horizontal 




Atmospheres 
of Pressure 



Fig. 11a.- — Horizontal borehole profile. 

Figure 11a illustrates this simple principle, being an 
actual example from a German potash mine where a fluid 
of 1.275 sp. gr. is being employed. To get the ordinate 
at the length 340 m., where the gage has registered 2.5 
atm. of pressure fall, proceed thus: 

10 X 2.5 



1.275 



= 19.60 m. 



and similarly for the length 500 m. registering 4 atm. fall: 

10 X 4 _^ __ 
-3^275-= 31.36 m. 

h. When the borehole deviates upward, the pressure is 
read at each desired spot by sending in the gage on the rods 



AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 33 

to the place noted and then extracting and reading. Or, 
as said before, a continuous pump pressure record is 
kept. 

The borehole depths read from the rod are entered as 
abscissae and the computed deviations from the horizontal 
as ordinates, as shown in Fig. 11a above. We thus get a 
line showing the course of the borehole. When the 
actual borehole is not intended to be horizontal the depths 
are projected, otherwise we get foreshortening errors. To 
lessen errors we may plot true borehole lengths against 
measured pressures direct. These methods are not affected 
by the smallness of the hole.^ 

Brigg's "Clinoscope." — This is another and more recent 
method of measuring the deviation of horizontal boreholes. 
It consists of a mercurial transmitter and Wheatstone 




d- e" d'' ^ J 

Fig. 12. — Brigg's clinoscope, vertical section of transmitter. 

bridge recorder, the tilting of the mercury into the horizon- 
tal position varying resistances which are measured by the 
bridge. 



^ 



,^7V 



~TT1I 
m j u 



Fig. 13. — Brigg's horizontal clinoscope. Plan of transmitter. 

In Figs. 12 and 13 is shown the transmitter which is a 
fiber box half filled with mercury g in the container d. 
Two circular pits at ^, i (Fig. 13) are connected by a slot 
s, the surface of the mercury, when the transmitter is level, 

1 Thiele, p., Verfahren zur Ermittlung der Abweichung von Horizon tal- 
bohrungen in der Vertikalebene, Kali, p. 32, Jan. 15, 1913. 



34 DEEP BOREHOLE SURVEYS AND PROBLEMS 

being at g. Two parallel resistance conductors a^ and a^ 
and a steel needle c pass through the fiber lid I. The 
needle connects the mercury to earth by way of the trun- 
nion n, the case e and the borehole lining. By dipping 
into the mercury the conductors are connected in parallel. 
Any change of inclination alters the length of conductors 
immersed, and thus the relation between the resistance of 
the conductors is a direct function of the tilt. This rela- 
tion is determined by means of a Wheatstone bridge which 
will be detailed later when discussing Professor Brigg's 
"clinophone" for vertical boreholes. The most disagree- 
able feature of the apparatus is the employment of mercury, 
which is an unsatisfactory medium to employ in mining 
owing to its so easily becoming dirtied and thence unreliable. 

THERMAL SURVEYS 

These are usually resorted to in cases where we need 

1. The geothermal gradient of the strata of a given area. 

2. To investigate the frost columns in a freezing shaft. 

3. To employ geophysical data in oil zones, etc. 

4. Purely scientific researches. 

They are purely thermometer surveys undertaken with 
some special form of maximum or minimum thermometer 
using various fluids and systems of calibration. Numerous 
devices^ have been invented to meet these needs, and in 
all cases it is necessary for the apparatus to remain in the 
hole some hours in order to acquire the temperature of its 
surroundings. 

a. Measuring Decrease of Temperature. — The Mom- 
mertz apparatus (Fig. 14) is one of the best known low- 
temperature contrivances used in borehole temperature 
surveys, i.e., in freezing shafts. A sheet-iron flask a 
contains a liquor which can withstand great cold, and this 
vessel is closed by means of a wooden plug. It hangs inside 
another flask c and between them is an insulating space 
on the vacuum-flask principle of exhausted air. The outer 

1 See the final chapter of Ambronn and Cobb's "Elements of Geophysics " 
McGraw-Hill Book Company, Inc., New York. 



AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 35 



flask has a screw top and suspending device. Its base is a 
pointed lead end. 

After the flask has hung a long time at the spot being 
measured, it is rapidly taken out and the temperature of 

Shaft ,d Freezing Pipe 




Lead d» '"Vacuu^ 

Fig. 14. — The Mommertz low temperature borehole thermometer. 

the solution read. This gives the temperature at the said 
spot after due allowance for the fluid being used. The 
time needed for the apparatus to assume the temperature 
of its surroundings is decided by trial for each case. 
The results are more or less approximate 
but useful. 

b. Measuring Increase of Temper- 
atures. — There are many kinds of maxi- 
mum and minimum thermometers in 
use. A favorite type of maximum ther- 
mometer is that in which the capillary 
is left open and ground off into a fine 
point with a reservoir surrounding it for 
the overflow. This overflow can be 
measured in various ways against known 
bath temperatures. The Hallock^ type 
has a secondary capillary for measuring 
the separated mercury. 

A well-known type of maximum and 
minimum thermometer is that of Six 
(Fig. 15) in which the liquid is alcohol 
in the tube A at the end B of which is a thread of mercury 
BC, the remaining part of the thread and part of the bulb B 
being again alcohol. The former end of the thread is for 
minimum and the latter for maximum readings. There are 
two indexes, one of glass the other of iron or both of glass 

1 Johnson and Adams, Econ. Geol., Vol. 11, pp. 741-762, 1916. 




Fig. 15.— The Six 
maximum and mini- 
mum thermometer. 



36 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



with side springs of steel as at G. For the bottom index 
glass is used. Glass being wet by alcohol the index 
retreats with it owing to capillarity and on rise of tempera- 
ture the alcohol flows past it without moving it, the spring 
also holding it; thus we get the minimum reading E. 

The upper index may be of iron, since alcohol does not 
wet iron, so that on rise of temperature the iron is pushed 
up and remains there when the column falls, showing the 
maximum temperature F. Otherwise the spring glass 
index is used. These can afterward be reset by a small 
magnet acting on the springs. Full accounts of up-to-date 
thermal survey methods can be obtained elsewhere.^ 

Length Recorder for Use When Inspecting Ropes. — 
This device 2 is now employed for hoist ropes, and lowering 




Fig. 16. — Elevation. 



Fig. 16a.— Plan. 



ropes for valuable apparatuses and is used to enable a rope 
inspector to find the position of broken wires or worn or 
distorted places accurately to within a few inches. In 
Figs. 16 and 16a a measuring wheel a, grooved to suit the 
diameter of the rope d, is kept in driving contact with the 

1 Van Orstrand, C. E., Apparatus for the Measurement of Temperatures 
in Deep Wells by Means of Maximum Thermometers, Econ. Geol., Vol. 19, 
pp. 229-248, 1924. 

McCuTCHiN, J. A., Bull. Amer. Assoc. Petroleum Geol., Vol. 14, No. 5, 
p. 536, May, 1930. 

Seifert, C, Fortschritte Mineral, Bd. 14, Part 2, pp. 167-291, 1930, for 
notes on geological thermometers and bibliography. 

^ The firm of Reinhard Wagner, Bergwerksdarf Oberhausen (Rhld), 
Germany; see also Gluckauf, Dec. 10, 1929. 



AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 37 

latter by two rollers h, c, carried by a frame e. The bearing 
pressure on a is regulated by the screw h adjusting the com- 
pression of the spring g. The base plate p is notched at 
r, and the end piece i of the frame / is detachable, so that 
the apparatus can be put into position round the rope. 
The frame / is mounted on a beam I carried by the springs 
and bars m, n. The castors q, mounted on vertical pivots, 
ride on the platform on which the inspector stands. The 
spindle of the wheel a is coupled directly to the recording 
train k, which indicates directly the length of rope that has 
passed a at any particular moment. The complete 
apparatus, which has proved quite satisfactory in practice, 
weighs about 57 lb. 

Construction of Borehole Sections or Profiles. — Obvi- 
ously it is only possible to portray the course of a borehole 
with any degree of accuracy by referring the observed 
data all to one plane. Having the depth and inclination 
data at hand, there are three methods of plotting these in 
any arbitrary vertical plane ^ viz.: 

1. Plotting the angle from the point where recorded 
down to the next recorded point. 

2. Reversing 1 by plotting upward to the preceding 
recorded point on the chart. 

3. Averaging 1 and 2 by plotting at the point on the 
chart either way, downward and upward, halfway to meet 
subjacent and superjacent plotted points obtained in the 
same way. 

Since methods 1 {A Fig. 17) and 2 {B Fig. 17) assume no 
gradual change of dip as usually obtaining in practice, 
but imply sudden regular dip changes, they are not now 
employed or recommended. Method 3 (C Fig. 17) will 
enable us to average subjacent data and plot this mean. 
The three hues A, B and C (Fig. 17) are plotted on the 
assumption that the hole deviates in one plane, say the WE 
plane of the paper. If a hole has been assumed to bear in 

^ These methods are also discussed by Prof. F. H. Lahee, Bull. Amer. 
Assoc. Petroleum Geol., Vol. 13, No. 9, p. 198, to which we are indebted for 
Fig. 17. 



38 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



only one plane (a common error of borehole chart makers) 
and it is later decided to allow for lateral directional devia- 
tions, or for depicting any borehole data in one plane, 
proceed thus: 

In Fig. 17a the profile of C (Fig. 17) is reproduced dotted 
and the hole is assumed to have the C hole dips and depths 



ABC Surface 




























1 


















1 


















'; 


















\s° 








mo 


' 








1 
1 


















>>7° 


















1 
1 


















I 
\ 












N55 


°E_ 





_a. 


JP° 






lood 












K 


\J 


} 






N2S 


°E 








f 
















^\ 




>~ 


V 












\j 


J 


^'^: 






'~ 


'~ 


~,~ 


7i 


^ft 


■27" 

\ 


o30 


00'' 








e^ 


\ 




\ 


\ 


NM. 


UJV_ 


— - 


— 


-^ 


k- 


Vk 


^f 












/ 




\ 


"^ 


\ , 








e', 


/ 






V 






Fig. 176. 



um^-" — ' 



Fig. 17. Fig. 17a. 

Fig. 17. — Section showing methods of plotting deviation of boreholes where 
readings are made at intervals and angular deviation is assumed to be all in same 
vertical plane. 

Fig. 17a. — Section showing a hole wandering in three dimensions revolved into 
the WE plane. 

Fig. 176.— Plan of Fig. 17a. 

throughout but alters in azimuthal directions from point a 
as shown on the left of the figure. Our problem is to 
visualize the borehole in the WE plane as in the previous 
Fig. 17. As ah is now bearing N.55°E. rebat it 35 deg. 
to ah') project this line to a6^ and drop perpendicular 
to the depth line of h at h^. (Imagine a to be the apex 
of a cone of side and dip ah with the new ah 35 deg. out of 
the old ah plane ; the actual depth and length of the new ah 



AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 39 

are unaltered except for the distortion due to projection.) 
Join ab^ and draw h^Ci parallel to be. The hole is now 65 
deg. out of the WE plane; slew b^Ci this amount to b^c' 
and project to b^c^ getting c^ on the c depth line as previ- 
ously. Join b^c^. In the same way get the due north part 
of the hole cd to show a vertical dd^ only, since it can have 
no lateral trend in the WE plane of the paper; and so on 
to e^, the last length being an extraneous addition to C 
(Fig. 17). It would be well to smooth a curve through 
these constructed points, and the same applies to the plan 
view of Fig. 175. 

Borehole Models. — These are very useful and instruc- 
tive adjuncts to any scheme of deep boring or precision 
boring, as in freezing shafts. Thurmann of Halle, Saxony, 
constructed the interesting and helpful model shown in 
Fig. 18 in 1909 to assist in visualizing the relative trends 
and positions of boreholes in a freezing shaft frost wall. 
It will be seen that he merely erected discs of sheeting or 
millboard at depths on the central rod scaled from the prog- 
ress chart, the said rod representing the shaft center. 
Thus, in the figure, the dots on the discs represent the posi- 
tions of the boreholes at the various levels or depths. The 
dotted line shows the position of a supplementary borehole 
to deal with the wide space in the frost wall between bore- 
holes 2 and 3. 

Figure 19 shows a glass model of the Chanslor-Canfield 
Midway Oil Co.'s No. 96 Olinda oil well in California, one of 
the deepest wells in the world. It is thought that some facts 
relating to the true shape of the course taken by the lower 
part of the well, obtained from a study of the model, 
would have remained unknown without its aid. 

The model is seen to be easily constructed from depth 
planes scaled from the boring logs and the positions of 
the instruments on each plane surveyed as shown. The 
bottom plane surveyed is 6,948 ft. deep. It is conceiva- 
ble that valuable results may be had from models outlining 
the course of well or boreholes and these would be more 
exact than sketched-in hypothetical underground contours. 



40 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



In this particular model the vertical hue represents 
the plumb line from the derrick floor. The curved line 
is an accurate representation 
of the course of the drill 
hole through the formations. 
The model was made by- 
drilling holes through sheets 
of glass in the surveyed posi- 
tions of the hole at differ- 
ent depths. A black cord 
threaded through these holes 
represents the well. 

The Sperry-Sun Well Sur- 
veying Company of Philadel- 
phia also employs an attrac- 
tive and useful method of 
depicting deviation. They 




Fig. 18. 
Fig. 18. — Thurmann's borehole model. 




Fig. 19. 



Fig. 19.— Glass model of the Chanslor-Canfield, Midway Oil Co.'s No. 96 
Olinda oil well in the FuUerton, Calif., Field, showing the course of a very deep 
borehole. {After Anderson.) 

project the surface position of the borehole on to the 
lowest depth model plane as the center of deviation 
coordinates. From this axis the relative displacements 
are plotted at their respective depths (Fig. 19a). The 



AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 41 



finished model is then pasted up at the sides giving the 
borehole as one edge of a distorted prism (Fig. 196). 

Lesser Deflection Records for Short Holes and Small 
Deviations : The Plumbing Basket. — This method employed 
in plumbing holes which have not deflected more than 





CSI r:|- vD CO 

(a) (6) 

Fig. 19a and b. — The Sperry-Sun Well Surveying Co.'s model. 

the borehole width, is often resorted to, since it is rapid 
and cheap. It was evolved by the Parisian firm Entreprise 
generate de fongage de putts etudes et traveaux de mines ^ 
It is much appreciated in surveying freezing shaft holes and 
prospect holes. It^ consists of a receptacle or basket filled 
with lead and let down into the hole on a hawser. The 
basket A (Fig. 20) is slightly less in diameter than the hole. 

^ Cavallier and Daxibine, Annates des mines, Paris, 1900. Series 9, 
Vol. 18, p. 392; Kohler, Bergbaukunde, Vol. 6, p. 634; Berg und Hutt. 
Ztg., p. 276, 1901. 

2 Schmidt, Trans. Inst. Mining Eng., Vol. 52, No. 2, p. 178, 1917; 
Erlinghagen, Gluckauf, p. 705, June 8, 1907. 



42 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



It is preferably, but not necessarily, suspended from the 
pulley S over the hole center C at the surface. The dis- 
tance CB varies in amount and bearing according to the 
deflection. If this suspension point >S is at a height h 
above, and the basket A at a depth D below, the surface 
and the measurable distance CB be called 
m, then the deviation X of the hole is 
obviously 

D + h 



iii}ii/nni/ii/i/i/ 




X ■= m -\r X 



m 



h 



(2) 



Fig. 20. — The lantern 
basket method. 



Erlinghagen^ simplified the process in 
a survey of freezing shaft boreholes for 
the shaft sinking firm of Gebhardt- 
Nordhausen. He employed a drum of 
0.314 m. diameter, i.e., 1 m. circumfer- 
ence, which carried a wound copper wire 
exactly 10 m. above the center of the 
mouth of the hole. It carried a heavy 
weight or plumb bob which moved freely, 
allowing the wire to take up an exact perpendicular posi- 
tion. A crosspiece with two measuring lines at right angles 
is fixed on the hole mouth to facilitate reading. The depth 
is taken from the number of unwound coils from the drum, 
each being 1 m. The computation (2) above now becomes 
^ ( D + 10 \ 

The method is not bound to fail when the wire fouls the 
sides of the hole, for in case of the hole deviating back to its 
original position at greater depths the wire will hang free 
of the sides. The method can be applied for depths down 
to about 300 ft., and instances of its successful application 
at over 600 ft. are on record. Certainly with big deflec- 
tions it is useless, but for surface and near-by subsurface 
conditions in most holes down to 100 yd. it is a useful 
auxiliary record. 

The all important dimension m is checked as follows 
(Fig. 1, Plate II). The coordinates {xiy-^ of C, the center 

1 Gluckauf, No. 23, 1907. 



AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 43 



of the hole at the surface, are known with respect to the X 
and Y axes, and the depth of any point A on the wire can 
be found, since we can get the length L of the wire direct. 




F16.5 





Plate II. — Illustrating the basket method. 



From the similar triangles SCB and BaA (Fig 1) right 
angled at C and a, we get 



CB _ SB^ .CB _ SB 

Ba ~ BA ^^^ Ca ~ SA 



and 



Ca = m -{- X = 



CB- SA 
SB 



Then, by coordinate geometry for the small length CB = m, 

CB = m = V(^r^^0M^7^7=^iIP (4) 

It will be seen that m is a function of the length L of the 



44 DEEP BOREHOLE SURVEYS AND PROBLEMS 

hole and L + I oi the wire. The azimuth of CB is easily 
taken from 

y2 - yi 

We first detect contact of the wire in the hole by m becom- 
ing constant, but, as already stated, it may vary again if 
the hole diverges back to its former direction later on. 
If this latter contingency arises it can be demonstrated 
as follows: Each deviation of the hole gives a new value 
in amount and azimuth for m, thus giving in a crooked hole 
a series of values, ai, a^, as ... a„ at different points 
1, 2, 3 ... n. At each of these points trace the bore- 
hole cross sections as shown in Fig. 4. Here the circles 
representing the circumference at the said points \ . . . n 
are projected downward on to a Une ai . . . n which is 
the continuous horizontal traverse of the deflections ai 
. . . (Zn in bearing. The centers of the circles are corre- 
spondingly subscript figured 1 . . . n. If the line SA 
do not touch the borehole sides, i.e., it is straight, we 
find it on the projected plan as the line can. That is to 
say, that if we make a vertical section of the borehole 
through can and draw in SA, it must not touch the sides. 
The points must be inside the borehole section circumfer- 
ence circles at the corresponding levels. If one or more 
do not obey this requirement, point S may be shifted 
for a new suspension and therefore new plan point C. 
Failing any agreement with the above demands, on moving 
S to the limiting lateral positions, the method ceases to be 
of utility any further. 

When point C has been retreated a distance d to C 
(Figs. 1 and 5) and the projection completed, the new 
deviation w is got from the new suspension and hole lengths 
a and h. Thus 

w = ^{a-Yh) ±d (6) 

Other but perhaps more troublesome methods have been 
adopted as modifications of the above method.^ 

1 F. Schmidt, op. cit., p. 180. 



AUXILIARY REGISTRATIONS IN BOREHOLE SURVEYS 45 

Errors of measurement arise from the following sources. 

a. Incorrect Adjustment of the Plumb in the Hole. — This 
arises often in unlined boreholes which frequently prevent 
the plumb fitting the hole like a piston. This mostly arises 
in chisel-bored holes which tend to ovality in cross section. 
Ten millimeters inexactitude renders the method unadopta- 
ble. The application of spring-centering mechanism to 
remedy this is not to be recommended. 

b. Sag of the Rope. — This occurs with long ropes holding 
small weights and it renders false readings of m. These 
errors increase, with the slope of the hole and its depth, 
according to the catenary law. The rope should be very 
light compared with the weight; or it may be ridded by 
centrally fixing the plumb at the measuring place and 
tensioning the rope.^ 

c. Incorrect Readings. — Inexactitude in reading m in- 
creases as m diminishes, greatly influencing the coordinates. 
Repeated micrometer readings should be made and the 
mean taken. 

1 See Wache's device, German Patent No. 3859, or Gliickavf, No. 46, 1904. 



CHAPTER III 

INSTRUMENTAL SURVEY OF BOREHOLES 

The determination of the course of boreholes by instru- 
mental means has occupied the minds of investigators 
since before the middle of last century. It received great 
impetus during the early eighties and the opening years of 
this century. Since the World War much work has been 
done, principally in the Mid-continent oil fields of America, 
South Africa and Germany in devising new means to the 
above end. From simple tests with plumbing baskets 
and by simple fluid apparatuses the progressive trend 
through various mechanical, optical, and photographic 
contrivances to the highly skilled gyroscopic methods has 
proceeded, until today the last two named means are being 
exploited vigorously. Probably the most widely adopted 
method in employment today is a modified form of fluid 
method, and it is now customary for contracts in drilling 
to specify a limiting permissible error in verticality of 1 
part in 100. Thus we are faced with a universally applica- 
ble standard of attainment expected of any method offered 
in the profession. The paramount requirements which 
have to be fulfilled by a successful device are as follows: 

a. It should record continuously on going down the 
hole and similarly make a check record upward on extrac- 
tion. Very few inventions meet this need. 

b. It should measure both the inclination and bearing 
of the borehole. This could be done by simultaneous 
registrations from one source or two initial sources register- 
ing at the same time. It is the great time-saving 
injunction. 

c. It should be under direct surface control with respect 
to registration as well as depth. 

46 



INSTRUMENTAL SURVEY OF BOREHOLES 47 

d. It should be immune from injuries due to water or 
mud pressures, chemical actions in the hole or strata, 
etc. 

e. It should be uninfluenced by local attractions such as 
are set up by magnetic strata, metalUc linings and rod 
magnetism. 

/. It should be simple and free from many technicalities 
and therefore less liable to derangement and needing less 
supervision. 

g. It should be easily understood and, if possible, capable 
of being read direct with few adjustments. 

h. It should be capable of registering at great depths, i.e., 
it should be of small diameter. This claim is a failing of 
most instruments. 

i. Its data should always be subject to check up and down 
the hole and also by different means. 

The several methods invented to investigate the course 
of boreholes may be broadly classified under the following 
general heads, though certain instruments may be included 
under two or more of these : 

1. Fluid methods utilizing the shape of the fluid outline 
in a cylindrical retainer. Such a fluid may be hydrofluoric 
acid, cement, gelatine, mercury, copper sulphate, wax or 
paraffin. 

2. Plummet and magnetic needle methods in which the 
dip and deflection are read on special arcs in the instrument 
or by core measurers aboveground. 

3. Electrical methods, wherein plummets are actuated or 
pricking cones are set in motion, also electrolytic deposition 
devices, wax-warming arcs, and other registration con- 
trivances. 

4. Pendulum methods either simple or compound. 

5. Photographic methods wherein the position of plum- 
mets and compasses is recorded, or where kinemato- 
graphic records of successive positions of these, or direct 
photographic views of the unlined sides of the hole, are 
provided. Multiple photographic devices and multiple 
views of shaped notches, etc., are included here. 



48 DEEP BOREHOLE SURVEYS AND PROBLEMS 

6. Gyrostatic methods where the principle of the gyro- 
scopic compass is employed. 

7. Plastic cast methods in which set models of the hole 
and its core stump are provided. 

8. Pricker methods operated by electromagnet plungers, 
levers, plumb bobs or in any other way, on paper strips, 
soft discs or plates. 

9. Inertia methods wherein the inertia of a heavy rotating 
body is employed. 

10. Seismographic or geophonic methods in which 
vibrations caused on the surface by explosions or the vibra- 
tions caused by drilling, particularly cable-tool drilling, are 
recorded. 

The general subject of borehole investigation can thus, by 
the above methods, be broadly divided into two main issues : 

a. The actual survey of the course of the borehole in 
azimuthal deviation and inclination from the line of its 
intended course. 

b. Core orientation in which the original underground 
position of the core is established. It is, of course, limited 
in its field of application by being only applicable to holes 
yielding cores. 

The two main branches a and h of our subject necessarily 
merge one into the other by reason of their close relation 
and the instruments employed being often of dual utility. 
Core orientation provides useful information as to the 
direction and amount of stratigraphic dip; information 
very difficult to obtain when boreholes incline through 
inclined beds. This will be seen by Fig. 21, where we will 
often meet the difficulty of having unreliable data as to 
whether a or ai is the truthful vertical thickness of the seam. 
The great value of core orientation surveys in fields insuffi- 
ciently mapped geologically, as in wild-cat ventures, is 
obvious; also where evidence is misleading or misinter- 
preted, as often in unconformities, asymmetric conditions, 
hidden dislocations, alluvial deposits and where we get 
change of facies.^ The retention or rejection of accumu- 

^ Macready, G. a., Bull. Amer. Assoc. Petroleum Geol., May, 1930. 



INSTRUMENTAL SURVEY OF BOREHOLES 



49 



lated data bearing on the problem will be decided by this 
core knowledge. Also the probable line of development 
in the field concerned. It is singularly useful in seeking 
index beds or marker or key beds and therefore decides 
the spacing of holes and life of a lease. 

It is considered that shale with a dip over 5 deg. is the 
most favorable stratum for core orientation, since dips are 
rarer in massive formations. Hard sands are more objec- 
tionable owing to their wearing out the cutters, and soft 
sands tend to crumble and plug the barrel ; also false bedding 




Fig. 21. 



occurs more frequently in sands. The chief difficulty is 
the transporting of the cores to the surface in a satisfactory 
condition. 

At all events sufficient has been said to show that the 
practice of borehole surveying and core orientation has 
progressed far since the day of Dr. Newell Arber^ who was 
rather emphatic in disclaiming the reliability of any 
methods purporting to show the direction of dip of beds in a 
borehole. 

In all methods of borehole surveying and core orienta- 
tion, one of the prime factors influencing the choice is the 
cost, since the cost consists not only in the actual expense 

1 Geology of the Kent Coalfield, Trans. Inst. Min. Eng., Vol. 47, p. 694. 



50 DEEP BOREHOLE SURVEYS AND PROBLEMS 

of the survey but also the time loss which could otherwise be 
taken up in drilling. 

According to recent findings^ the direct and indirect 
costs of making separate directional surveys with every 
500 ft. of additional hole amount approximately to 2 to 3 
per cent of the total cost of a producing well. The increased 
cost due to the changes in drilling practice in order to 
keep a hole straight and the cost of straightening a crooked 
hole ordinarily range from 5 to 10 per cent of the total 
cost of the hole, depending upon the work required to 
correct possible crooks in the hole. Thus apart from 
any considerations (in oil-well drilling) of improved 
spacing, better drainage and higher recovery per well 
and per acre which arise from correct surveying of boreholes, 
it will be seen that good surveying will tend to lighten the 
burden of straightening costs. This because it also yields 
enlightening data on dry wells and causes of dryness. 

Accuracy of Borehole Surveys. — Respecting the accuracy 
to be expected in a contract for borehole survey work it 
may be mentioned that demands here vary in stringency 
with the importance of the survey. Freezing shaft con- 
tracts frequently require a minimum limit of reliability 
in readings of 1 in 150, i.e., 1 off the vertical for every 150 
deep. Or again they may desire a deflection record not 
exceeding 2}^ deg. off the vertical, since beyond this no 
frost wall is safe at depths of over 100 yd. Hence the 
desired accuracy decides the type of apparatus being 
employed, whether crude methods with unreliable direction 
records, like pricking bobs without orientated rod couplings, 
or the more precise pendulum and gyroscopic methods which 
often yield accurate results up to 1 in 3,000. The purpose 
of the boring will therefore, in the end, decide the nature 
of the survey apparatus. The purposes for which boreholes 
are put down are as follows: 

1. To locate a seam, stratum, oil zone, salt or any other 
mineral. 

1 Murphy P. C, and Judson, S. A., Bull. Amer. Assoc. Petroleum Geol. 
Vol. 14, p. 603, May, 1930. 



INSTRUMENTAL SURVEY OF BOREHOLES 



51. 



2. To obtain the thickness, depth and constitution of 
such deposits. 

3. For shaft sites. 

4. For conducting electric cables (Fig. 22), steam and 
compressed air pipes, also haulage ropes to the mine. 



- ,, , nConnechon Wooden Reel 

Several furns of \\ ^^ p^j^ Line^iT-kpn which Cable 
Wire around Reel, \^ ///■ ':'\ was shipped 



limbers 
supporfing 
Reel-\ 



Casing of 
Borehole ' 




(.a) 



Wooden Clamp holding 
fwo sf rands of Cable 



(b) 



777777777777777 .:;S 




(c)- Suspension Glamp 



Fig. 22. 



5. For hydraulic stowing. 

6. For utilizing any hydraulic head which peculiar geo- 
logical conditions may provide in old workings (Fig. 23). 



rSurface 
rrr7TTfrr->i 




+ 850' 



El A 800' 
FiQ. 23. — Ideal cross section of a synclinal basin. 



7. To aid ventilation by draining off gases. 

8. For circulating tubes when sinking by the freezing 
process. 

9. For cementation. 

10. For checking any other boreholes. 



52 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



This last item of check is probably the most important 
aspect of accuracy. If possible the method being adopted 
should be checked later by methods dependent on a 
totally different operating principle. Then the results 



Derrick Floor 




Plan View of oinOil Well 
ComparingResulis of Several Surve\/s 



Derrick^ -^ 
Floor I 




depth 



Fig. 24. — Plan of an oil well comparing Fig. 25. 

results of several surveys made under 
varied conditions. {After Macready.) 

could be compared graphically as in Fig. 24 (after R. P. 
McLaughhn) ^ Faihng this a check survey should be made 
in and out of the borehole as in Fig. 25. ^ The manner of 
compiling a check will be seen from Table VIII, wherein 

1 By the courtesy of Bull. Amer. Assoc. Petroleum Geol. (Vol. 14, No. 5, 
p. 586, 1930). 

2 Ibid., p. 588. 



INSTRUMENTAL SURVEY OF BOREHOLES 



53 



the old and tried method of acid etching is compared with 
a recent plunger-pricker method for amount of dip only.^ 

Table VIII. — Comparative Surveys of an Oil Borehole in the 
Seminole District, Oklahoma 



Depth, 
feet 




Acid-bottle reading, 
degrees, corrected 



252 








499 


2 





748 


1 


4 


1,005 


4 


7M 


1,257 


10 


12M 


1,360 


10 




1,512 


17K 


mi 


1,758 


17 


19M 


2,002 


24 


28 


2,094 


28 




2,268 


28 


32M 


2,502 


34K 


38M 


2,745 


38 


39K 


3,009 


40>-^ 


41 M 


3,255 


39 


40 3^^ 



However, these checks are relative and cannot be claimed 
as absolute; the only absolute checks are actual observa- 
tional ones as 

1. Where a hole is followed by a shaft or drift. 

2. A^Tiere a hole has been bored between known and 
occupied places, as between stopes, working seams, etc. 

3. Where boreholes deviate and meet; all methods thus 
registering the same meeting spot in both holes. 

^ Petroleum Engineer, December, 1929. 



CHAPTER IV 

CORE ORIENTATION 

Introductory Note. — This branch of instrumental survey 
in boreholes being the older of the two main divisions 
previously noted, we will deal with it first. It has not been 
so extensively employed as the other department of bore- 
hole surveying dealing with the course of the borehole 
proper. Among the chief factors not already discussed 
which either influence the relative positions of boring tool 
and strata pierced or provide useful evidence of the same, 
we may mention the following, of which a running record 
should be kept.^ 

1. The type, size, and dimensions of bit used. 

2. The size of drill stem. 

3. The size and depth of the hole. 

4. Weight of mud used. 

5. Pressure employed on the bit. 

6. Speed of rotation or number of strokes per minute. 

7. The stroke or fall in percussive boring. 

8. The weight on the tool in percussive boring. 

9. Rate of water circulation. 

10. Ease of running in and coming out with drill stem. 

11. Ease of setting the casing. 

The various orientation methods can be nearly all 
grouped into the four following classes: 

a. Orientating the core barrel by measuring or aligning 
the drill pipe out of the hole. 

b. Attaching an instrument to the core or core box in 
the hole during operation previous to extraction. 

^ See also a useful questionnaire by F. H. Lahee for the Research Com- 
mittee of the American Association of Petroleum Geologists, Bull. Amer. 
Assoc. Petroleum Geol., July, 1929, for notes on checking observations, etc. 

54 



CORE ORIENTATION 



55 



c. Lowering an instrument on to a freshly cut core and 
then extracting it with or without the core. 

d. Photographic devices for the walls of the hole. 
Kind's Method. — Kind's core drill is the earliest form 

known, having been employed in coal strata near Forbach 
in Lorraine in 1844^ using a free-fall percussion drill 
(Rotary core drilling was first adopted in 1861 by the French 
engineer Leschot) . 

Kind also made the first core orientation. The method 
has long been superseded and information thereon is 



rA^ 

^ 




Fig. 26. — Kind's borer. 



Fig. 27. — Kind's core breaker. 



scarce. It was employed in 1854 in Forbach yielding a 
half-meter core which was brought to bank in as unaltered 
a condition and position as possible. 

Figure 26 shows Kind's fork-shaped borer which provided 
the thin core 12 to 20 in. long and was then extracted. A 
core breaker a (Fig. 27) was lowered to tear off and lift 
out the core b; this breaker had a toothed inner cylinder c 
keeping the teeth d forced out during insertion and sus- 
pended by a cord from the surface. To prevent turning 
he employed two index arms held against the rods, one by 
a man in the derrick near the top of the drill rod and the 
other at the derrick floor. These arms aligned the pipe 
against twist. The method yielded cores of only about half 

iRedmayne, R. a. S., "Modern Practice in Mining," Vol. 1, p. 91. 
Macready, G. a., Bull. Amer. Assoc. Petroleum Geol., Vol. 14, 1930. 
KoEBRiCH, A., Pr. Zeitschrift, Vol. 36, p. 256, 1888. 



56 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



the width of the hole, and diamond drilhng with its small 
holes later on made it obsolete. A similar method was also 
applied by the engineer Zobel in Schonebeck in 1855.^ 

Lubisch's Method. — The boring master Lubisch improv- 
ed on Kind's method in the Upper Silesian mineral fields 
in 1887. He diamond drilled a core first without a core 
catcher, leaving the stub standing in the hole. Then he 
lowered a second tube (Fig. 28) over the stub and marked 
it in a definite manner respecting the meridian and later 
extracted it, orientating it as in Kind's method. It 
suited small holes better. In Fig. 29 the steel tooth of the 
orientating tube closes about the core and makes a definite 





Figs. 



28 AND 29. — Lubisch's core 
marker. 



^^. 



Fig. 30. — Vivian's pilot-hole core 
compass. 



mark which was expected to have a definite known surface 
orientation. After lifting out this marker device a core 
extractor was let down to bring out the scribed core. Now 
the scribed longitudinal mark is adjusted to the vertical 
plane by means of a spring pen hanging on the rods and the 
dip and strike read. Lubisch improved his apparatus 
later by adding a cap carrying a steel scriber which gave a 
mark at right angles to the side mark, and he also improved 
the joints to prevent twisting on insertion and extraction. 
Lubisch's advantage over Kind was in the more rigid 
hollow rods and the possibility of working in smaller bore- 
holes. For success the following demands, difficult and 
nearly impossible to attain altogether in practice, are to be 
fulfilled: 

1 Mitt. Markscheiderwesen, Heft 4, p. 37, 1902. 



CORE ORIENTATION 57 

1. There must be no mud or cavings between the core 
and borehole walls. 

2. The core must be sufficiently rigid so as not to fracture 
on extraction and to preserve the markings. 

The changing of the rods, etc., make condition 1 very- 
difficult, since we then interfere with the rinsing. In 
very hard rocks condition 2 might be impossible, owing 
to lack of clarity in the marking. In soft rocks this latter 
condition is impossible. These methods, it will be seen, 
take up much time and are not now in operation. 

Vivian's Method. — The method of the American diamond 
driller, Vivian,^ marked a new departure and significant 
advance in core orientation. He drilled a small pilot hole 
of a few inches diameter and lowered a small instrument 
case into it, so that a part of it was fixed in the pilot hole. 
This case held a compass needle clamped by a weight used 
in setting the case. When the core was recovered the case 
was also recovered attached to its upper end. Figure 30 
shows the compass c and its arresting apparatus a and the 
tap neck 5 in the pilot hole d. The needle, free at first, 
is fixed by letting down the weight. This was all retrieved 
later in the normal method of core catching. Above- 
ground the needle is freed and the core turned to give the 
position before arrest. The core now is in the same posi- 
tion as in the hole, and so its dip and strike can be obtained. 
The demerits are 

1. The apparatus is almost, if not quite, impossible of 
use under a big head of water pressure. 

2. Cavings filling the pilot hole as when concussion occurs 
during coring, rupture of the core and mud. 

3. In small holes the pilot hole thins the core itself to a 
too fragile degree, the wall thickness in diamond boring 
needing to be at least 12 to 18 mm. and in addition we must 
consider the play on both sides. 

4. A compass can not be set vertically true in a small 
core. 

1 Trans. N. E. Inst. Min. Eng., p. 45, 1881-1882. 



58 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



5. Great loss of time in boring pilot hole, exchanging rods 
and extracting cores. 

Vivian's method has had very little usage owing to the 
small probability of success. 

Kendall's Apparatus. — This apparatus was invented by 
P. F. Kendall at Owen's College, Manchester, in 1887, 
and it was arranged to be set in a pilot hole like the Vivian 
method, but the compass in the case was clamped by 
lifting off the weight of the setting tool. A core was then 
taken out with the compass attached to the top of it. The 
magnetic compass is attached by means of a peg or cement 
to the top of the core and left standing by the boring tool, 

, c. b 




Fig. 31. — Kendall's apparatus. 

and the needle is automatically locked by the release of a 
spring when the lowering tool is withdrawn. In Fig. 31 
is shown the compass box a with its strong screwed-on hd 
6, and inner glass lid c held by a screw collar. The pillar 
d bears the compass card e while / is a tube sliding on d 
flanged and serrated at the top. About this is a spiral 
spring % pressing the flange upward for its toothed edge to 
grip the compass card e against the glass lid c. A slot and 
pin on d prevent rotation of the tube. The catch lever g 
holds down / by the flange when the apparatus is set ; it 
turns on pin g' on the box floor. The floor trigger h 
hinged to g has a flange and spiral spring K for operating the 
catch lever and permitting / to grip the card bearing the 
needle. An India-rubber ring under the card aids the teeth 



CORE ORIENTATION 



59 



grip, preventing sliding. In action the lowering tool holds 
trigger h out. At the core and after sufficient time has 
elapsed and the needle has come to rest, the lowering tool on 
being withdrawn releases the trigger h, throwing the catch g, 
allowing/ to ascend and lift the card off its bearing, pressing 
it against the glass lid c. 

The core is now wrenched off and lifted to bank and on 
unscrewing lid h the orientation of the core is read. The 
weaknesses of the apparatus are the 
same as those of Vivian's apparatus; 
chiefly insufficient protection against 
water pressures which is more necessary 
here, since there are more moving parts. 
The drawbacks of space demands in the 
core and trouble in the measuring 
method have not been removed any 
more than in Vivian's method. Again 
there is the liability of premature dis- 
turbance of the needle due to shocks as 
in wrenching off the core. There appear 
to be as little data in professional 
literature respecting its actual employ- 
ment as in the case of Vivian's apparatus. 

Wolff's Apparatus. — This device was 
invented in 1889,^ and marked the 
introduction of a new feature. In this 
method the apparatus was lowered ^^° 
over a stub of core in the hole and 
a mold taken. Clockwork was used 




////////// r // y///. 




32.— Wolf's core- 
cast device. 



to 



clamp a 

magnetic needle after a predetermined time. The core 
was then removed and orientated from the clamped 
needle attached to it. Figure 32 shows Dr. Wolff's method 
for fixing the compass in a mold or cast, the latter being a 
plastic material. The apparatus consists of a two-part 
tube A1A2, with a lead filling B, which serves to guide and 
hold tight the lower plastic mass giving the imprint of the 

1 See German Patent, 47, 221, Oct. 27, 1888; also Osterr. Z. Berg-Huttenw., 
Nos. 41-43, 1906. 



60 DEEP BOREHOLE SURVEYS AND PROBLEMS 

core below. Between Ai and A 2 is a compass box C of 
non-magnetic material with a compass D and a clockwork 
mechanism E screwed on tight, which has been set to 
operate at a predetermined time. The plastic mass having 
been lowered over the core stub and allowed to harden, 
and the needle arrested, the apparatus is raised and the 
position noted. The core is now lengthened by the usual 
coring process, wrenched off and raised to bank. Here it is 
fitted to the impression in the cast and turned with the com- 
pass until the needle plays in the position previously noted. 
The dip and strike can now be read. 

The method appears theoretically to be well suited to its 
purpose and it has the advantage of increased protection 
for the compass and clockwork mechanism, and also the 
time taken in insertion and employment is shorter than in 
previous methods. However, its success depends on many 
factors which preclude its adoption in general practice. 
Thus we have the following disadvantages: 

1. Mud and cavings prevent good impressions. 

2. A flat upper fracture on the core surface is more suited 
to the process than inclined ones, because very inclined 
wrench faces prevent good impressions. 

3. On inclined core faces tube A 2 is likely to slip and ren- 
der results faulty. 

4. The core must be solid and fast; this is not possible 
in shales, schists, etc. 

5. On fitting the mold aboveground the core must have 
been raised in exactly the same position as it had when the 
mold was taken, and this is almost impossible. 

6. The minimum size of core is 5 to 6 cm., otherwise the 
impression is not clearly recognizable. 

7. Even with all the above conditions fulfilled, taking 
the mold, lengthening the stub, wrenching it off and raising 
it occupies too much time. 

Koebrich's Apparatus. — In this method the position 
of the compass with respect to the core is ascertained 
by means of a clearly cut mark on the top face of the core 
with the aid of the apparatus shown in Figs. 1 to 6 (Plate 



CORE ORIENTATION 



61 



III). In Fig. 1 (Plate III) note that the cross-guided heavy 
rod a is connected to the straight bit chisel ai by means of a 
conical joint. The bit has a small recess X on one side. 
Over the heavy rod the gun-metal body K is fixed by a 
conical Oynhausen joint hh' (Fig. 2). The bored-out non- 
magnetic box K encloses a watertight ground-in stopper 



r "'oi 1 




F16.6 




F10.3 




F10.5 



Plate III. — Koebrich's core orientation apparatus. 



V. Inside the cap are a clock and compass and the compass 
is arrested by the wing F of the clock U (Figs. 3, 4) moving 
clockwise, taking with it the lever arm h of the double- 
armed lever 1, 2, 3, (Fig. 5). In this way end 3 of the lever 
which is bent round engages the arresting spring / and frees 
it. This latter springs up and clamps the needle against 
the cover plate of the compass. A circular graduation 
about the axis of F is arranged so that the interval between 



62 DEEP BOREHOLE SURVEYS AND PROBLEMS 

the divisions is 1 hr. The glass-covered clock Ues together 
with the compass in the frame G (Fig. 3). Four projec- 
tions m are provided in the housing so that the mutual 
positions of the clock and compass are maintained by fitting 
into corresponding niches in the frame. In order that the 
frame itself be immovable with the gun-metal box it has 
four studs n fitting in recesses in K.^ 

For setting up the apparatus the angle between the niche 
in the end of the chisel and the north end of the needle 
must be known. Koebrich himself gave the direction 
of the chisel the 12 o'clock line of the compass and let 
the niche of the chisel direct itself with respect to the north 
end of the needle. (The angle thus indicated is deg). 
In order to avoid errors in this indication the inventor 
has replaced all screw joints with conical joints. In action 
the procedure is as follows: Adjust the arresting device to 
act about 15 min. after all the rods have been let down 
in the hole. Then assemble the apparatus as in Fig. 3 
and suspend it in the hole until about three-quarters 
of the stroke off the floor of the hole. Now a powerful 
blow is struck with the chisel, producing a mark (Fig. 6) 
on the rock which will show the nick mark of the chisel 
in suitable rock. After the blow the chisel remains until 
the needle is set and is then pulled out and the indicated 
time read off the compass. In the usual way of core boring 
a core is made, lifted out and orientated. The free-playing 
compass is held so that the angle between the north end 
of the needle and the nick projection marked on the core 
has the same value as when the apparatus was assembled, 
and according to Koebrich deg. The compass is turned 
so that the needle reads the previously indicated hour, 
thus giving the position of the core as it had formerly been 
in the hole. The dip and strike are now easily obtained. 

Koebrich's apparatus was a big step forward over preced- 
ing methods both in respect to protection from internal 
injury by boring operations and in respect to the trust- 

1 Freise, F., Die Entwicklung der Stratameter, Osterr. Z. Berg-Hiittenw., 
No. 42, p. 546, 1906. 



CORE ORIENTATION 63 

worthiness of the results. The apparatus is durable and 
simple and will withstand considerable water pressure, 
but the difficulties of clockwork devices are here only 
ameliorated, not prevented. It has many disadvantages : 

1. In friable marls, medium sandstones, weakly cemented 
conglomerates, etc., it is useless because here we get neither 
core nor marking satisfactory. 

2. A second blow, on account of the rod tor- 
sion, would mean a turn of the chisel and a com- 
plication of the orientation. 

3. Much time is used up in altering the tools for 
marking, coring, etc. This often takes 6 to 8 hr. 

MacGeorge's Core Orientation Method. 
MacGeorge (1884) was the first to appreciate the 
importance of obtaining the inclination of the 
core at the time of orientation. He used a brass 
tube set eccentrically, and furnished with a bell 
mouth below, the office of which was to receive 
the extremity of any piece of core left standing 
at the bottom of the bore, and, as the apparatus 
is forced down, to press on one side and break 
off the piece of core. 

A plummet a (Fig. 33) is suspended midway g^^ 
in one or more phials of warmed gelatine h in ^^ 
suitable containers in the core catcher. The 
whole apparatus being now left unmoved for 2 or 3 hr., 
until the fluid in the phials has cooled and set, is 
withdrawn, and the core extractor unscrewed. The 
phial of liquid gelatine is firmly grasped and kept in the 
same relative position as the core in the borehole. 
The phial, by means of its internal indications, will 
enable the piece of core to be replaced in its natural 
position for observation, and thus there may be readily 
ascertained (by examination of the markings) the true dip 
and strike of the strata, or the underlie and bearing of the 
reef, of which it originally formed a part. We shall discuss 
the method further when dealing with MacGeorge's devia- 
tion device later. 



64 DEEP BOREHOLE SURVEYS AND PROBLEMS 

Gothan's Stratameter. — This device was invented in 
Goslar (Hartz) Germany in 1899 and is the first kind of 
orientating apparatus in which a recording contrivance 
is directly fitted to a rotary core barrel during coring. It 
has been used to great depths in Germany and is attached 
to a single-barrel core drill. It consists of an instrument 
case attached to the top end of the barrel, the case holding 
a magnetic compass (and in the Otto-Gothan device also a 
plumb bob), a soft sheet and a clockwork mechanism. 
The clock previous to lowering is set to trip at a chosen 
time. The core is drilled and stays until the clock trips, 
when the compass is clamped and the plumb bob dropped 
into the soft sheet, providing an indentation on it. The 
barrel is then withdrawn and the orientation deduced from 
the clamped compass and position of the indentation. 
Gothan also provided a swivel stand so that the position 
and inclination of the core may be reproduced to visualize 
the orientation. It has been frequently described.^ We 
shall describe the Otto-Gothan device later on. 

In Fig. 1 (Plate IV) note that the clockwork and compass 
are placed in a delta-metal box G which is fixed and guided 
by a second housing Gi. The first housing is fixed to the 
ring e screwed into the boring cylinder a. The fixing device 
for the magnetic needle I consists of a spring n fixed in the 
upper part of the clockwork and actuated from below 
by the conical rod o. While the needle is free rod o bears 
against a lug of lever p and holds its end pi away from the 
balance q. If the pointer r is set to any chosen number, 
on reaching this time number, spring n acts by a lug s 
engaging in the corresponding notch so that the small 
wheel Si connected to arm disc s raises up arm Vi. Thus 

iRedmayne, R. a. S., "Modern Practice in Mining," Vol. 1, 1925. 

Macready, S. a., Bull. Amer. Assoc. Petroleum Geol., Vol. 14, No. 5, p. 
565, 1930. 

Freise, F., "Stratameter und Bohrlochneigungsmesse," 1906. 

Ullrich H. and Werneke, H., Mitt. Markscheiderwesen, Heft 4, p. 38, 
1902. 

British Patent Nos. 2220, Jan. 31, 1899, and 21,183, 1901. 

U. S. Patent No. 649.636. 



CORE ORIENTATION 



65 





F1&.2 






Fig. 5 




Fro. 6 



FrG.3 
Plate IV. — Gothan's stratameter. 



66 DEEP BOREHOLE SURVEYS AND PROBLEMS 

the needle I is pressed up against the stay m and fixed. 
Simultaneously the stud o is freed from lever p and the 
spring t presses the lever end pi against the balance, thus 
stopping the clock. 

The core is broken off now and the whole raised to the sur- 
face. The boring cylinder, provided below with two marks 
A and B, is now unscrewed and the core top is free. The 
core is marked with a diamond or in color and then it is 
adjusted on a disc chuck v (Fig. 4) which has a shell u 
so that the marks coincide with the diametrically opposite 
marks Ai and Bi on the shell u and turntable v. The com- 
pass is now placed on this (usually on a top core shell Ui) 
and being still fixed is turned to occupy the same vertical 
plane as A, B or Ai, Bi (Fig. 3). On releasing the needle 
and letting it come to rest in its north meridian, the whole 
table is turned until the north end of the needle registers 
the previously noted time. The position thus indicated 
is that which the core had previously in the hole and thus 
the strike is obtained. 

Gothan's apparatus was the first to meet the demands 
of durability, simplicity and rapidity in manipulation with 
any measure of success. It has been used at great depths 
and experimentally tested to 100-atm. pressure for more 
than 2 hr. 

The casing mentioned above has a further non-magnetic 
rod connection of 4 m. above and about 2 m. of bronze core 
barrel below to protect it from local magnetic influences. 
Very satisfactory data on its application have been obtained 
by Professor Schneider, of the Berlin School of Mines, in 
Upper Silesia and Galicia.^ It has been used in depths of 
over 3,500 ft. 

It is a surer apparatus and greater time saver than 
Koebrich's method, because it brings the orientation 
marks and the core to the surface. It does not depend on 
chisel marks like the latter and also the check is made 
aboveground. Further, in Koebrich's method the core has 

1 Mitt. Markscheiderwesen, Heft 4, p. 40, 1902; also O. Erlinghagen, 
Gliickanf, No. 23, 1907, for tests at Aix-la-Chapelle. 



CORE ORIENTATION 67 

to be specially marked thus using up more time, while in 
Gothan's method the apparatus is actually a part of the rods 
so does not use up the time. Furthermore, it gives direction 
and amount of deviation. 

The demerits of Gothan's apparatus lie in the uncertainty 
of the measuring device and 

1. We do not know whether at the moment of arrest 
the needle maintains its correct relation to the strata. 

2. We cannot guarantee no twisting of the core on 
extraction, a tendency which increases with depth. 

3. Kicking of the core on wrenching cannot be avoided 
and this minimizes the reliability of the result. 

4. We do not know the state of the core, whether fast or 
loose, when the needle was arrested. 

5. Blunted core catchers cause faulty results. (For 
success a sharply defined core is required; also the core 
must be jerked off sharp and its lower face must be clean 
fractured without traces of friction markings.) 

Meine's Stratameter. — Dr. Meine of Berlin invented his 
well-known apparatus about 1902.^ He utilized a messen- 
ger ball dropped down the drill rods instead of a clock to 
trip a clamp for locking a compass needle on a core barrel. 

The apparatus (Fig. 34) consists of a lower part a, which 
can be unscrewed from an upper part b, the former having 
a bored-out portion holding a needle and arresting lever. 
The short arm of the lever / can be depressed by a ring g 
lifting the needle against the plate p and arresting it. In 
the hollowed part of the lower portion the internal part c 
of the apparatus rests on a ring of wood fiber or like 
tightening material, and it can be screwed up tight by a 
screw nut d. Through the center plate c goes the rod h 
rotatable about its long axis through a stuffing box. This 
rod has top and bottom lugs, the lower one engaging 
with a flange of the ring g causing it to turn, while the upper 
or eccentric lug k stands tight under the conical point of the 
pin I. When the latter pin descends vertically the lug k 

1 British Patent No. 16,514 and German Patent No. 154,496. 



68 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



is pushed aside, so that the rod h turns and with it the ring 
g to arrest the needle /. 

The descent of the pin I cannot be directly effected by 
the rinsing water, but when the lead ball n is dropped 
in the rods it deflects the current and its surface is sufficient 
to considerably hinder its momentum. When ball n meets 
the pin I the obstructed current throws a back pressure 





Fig. 34. — Heine's stratameter (origi- Fig. 35. — Heine's stratameter (modi- 
nalform). fied form). 

on the rinsing pump manometer. Thus the ball with the 
water presses down pin I through its friction socket to 
actuate eccentric k on rod h and so arrest the needle. 
This instant of arrest can be read on the pump manometer 
by a visible back kick of the indicator, because then the 
water gets a freer passage through the channel o to the floor 
of the borehole. The whole process lasts only a few 
minutes. Now the rods including the stratameter, core 
barrel and core are lifted out and the north direction 
of the needle transferred to the core. 

The above apparatus has a whole series of structural 
modifications, as for instance in Fig. 35. Here the arresting 



CORE ORIENTATION 69 

rod e is borne by two rectangular shoulders through the 
internal housing by means of stuffing boxes or friction 
sockets in the base plate. These lugs are double armed 
and are connected by a right-angled rod k connected to 
a lever v through the arm w to the magnet needle. The 
upper lever is so arranged that when descending the rod e 
moves its inner arm downward and the outer one upward. 
In this way k is in tension, pulling, and the forked end of 
lever w presses down a plate m which touches a leather 
based rod n. As soon as m is let down the spring jp presses 
against it and prevents it retreating. The leather ring o 
now lies on three teeth in the head of the needle and thus 
holds it fast in its natural north position. 

In order to detect the presence of a magnetically dis- 
turbed region the precaution is taken of placing another 
needle about 30 in. below the first one and operated 
simultaneously with it. From their difference of directions 
the presence of a magnetic disturbance can be recognized 
and so a true orientation can be made. 

Heine's stratameter is a simple, sure and easily manip- 
ulated apparatus well fitted for its task. It is insensitive 
to water penetration. Thus sand and the like can not enter 
to hinder the action of the finer parts, and, moreover, these 
parts are easily accessible for inspection and cleaning. 
It is very convenient to operate, since it does not interfere 
with the ordinary working processes of the borehole. The 
apparatus is inserted in the rods once and for all, it being 
only necessary to drop in the ball and observe the rinsing 
pump gage when a reading is required; then the core is 
wrenched off and the whole raised to the surface. It 
fits the tools and no extra objectionable extractions are 
needed. Any doubts in the results obtained are due 
to the same causes as discussed for Gothan's method. 

Of the apparatuses in this class Gothan's apparatus is 
the greatest time waster and Heine's device one of the 
greatest time savers. The chief factors operating against 
Heine's apparatus are 

1. Shocks may cause the arresting pin to function. 



70 DEEP BOREHOLE SURVEYS AND PROBLEMS 

2. Slight rotation of the core on fracture in hard beds. 

3. Fragile cores. 

Thurmann's Stratameter. — The apparatus (Fig. 36) con- 
sists of a shell with a compass device. Above and 
below the shell are bronze rods; the one above is about 83 
cm. long and one below about 73 cm. long, as shown. 
The iron rods are equally distant from the needle, i.e., 
1 m., but this distance is not sufficient to cut out the disturb- 
ing influences in the vicinity. The device consists of a 
stratameter base A, the interior joint cap B and an external 
casing C. Cast on to A is a petroleum container D, in 
the floor of which the small pressure compensation tube R 
is screwed and in which a leather plug P moves like a piston. 
Over this, held by a safety bar St, is the compass box 
with the magnetic needle N. This is covered by a glass 
plate which can be screwed off. Under the needle lies 
the horizontal arm H of the arresting cone K on the base 
of the box which is held by the spring-pressed nut Mi 
and the spiral spring F. The rod of the cone extends up 
through the joint nut and a leather disc S placed over the 
rod prevents the penetration of borehole mud. A pressure 
or blow on the rod forces it down, thus pushing aside 
the arresting cone on to the erect arm of lever H. Its lower 
arm raises the needle from its seat, pressing it against the 
glass cover plate and holding it fast. 

Mud and rinsing water cannot enter because the internal 
compass box and the space about the tube R and the cone K, 
beside being spring compressed, is full of petroleum. The 
external casing is now fitted and the apparatus let into 
the hole. The procedure from here on is exactly as with 
Heine's apparatus. 

It will be seen that Thurmann's apparatus is very much 
like Heine's in form and manipulation. It has all of 
Heine's advantages over Gothan's apparatus and it exhib- 
its some small improvements on Heine's apparatus. 

A special advantage is that the interior of the apparatus 
is provided with a protective filling of petroleum against 
the entry of rinsing water. In percussive boring — assuming 



CORE ORIENTATION 



71 



it produces a core — Thurmann's apparatus is certain in 
action, since here shocks cannot bring about preliminary 
disturbance of the needle, a factor which is not provided 
for in Heine's apparatus. The internal construction of the 
apparatus is much simpler and the arrest of the needle 




^ 



^■5+ 



It 



Bronze 
Rods ^ 

73 cm.' 
long [ 



Fig. 36. — Thurmann's stratameter. 



Fig. 37. — The North German Deep 
Boring Co.'s stratameter. 



occurs much sharper than in Meine's device, because the 
transmission of the arresting action takes place by means of 
only two pieces of mechanism and not by means of a series 
of intermediate members. 

The North German Deep Boring Company's Strata- 
meter. — The North German Deep Boring Company of 
Nordhausen have produced a device of the stratameter 



72 DEEP BOREHOLE SURVEYS AND PROBLEMS 

type but somewhat different in construction. ^ In Fig. 37 
the tube Ri Hes inside a wide tube R2 (moved by the rods 
with nuts and spring) and carries in its upper part the closed 
compass box B filled with oil. The rinsing current escapes 
by way of the holes 0, 0, in the head of the core, tube Ri. 
When a determination is being made the external tube is 
lifted up so far that these openings are covered by the 
internal projections V of the external tube. In this way 
an excess pressure of water is set up which actuates a spring- 
loaded piston k a little further up through the bores n,n. 
This causes the rod S to free the needle which was hitherto 
fixed. After the needle has settled down, the external 
tube is lifted higher and when the water holes 0, are 
passed by Vi they are again free and the piston k is unloaded. 
Then the spring F again comes into operation and the needle 
is fixed orientated. It can now be drawn further so that 
the core, broken off by the core breaker on the external 
tube, can be raised to bank. 

The apparatus is in many ways similar to that of Meine 
or Gothan in principle and construction, but the needle 
is freed by the rinsing water pressure by moving the tubes 
relative to one another. The needle is also brought to rest 
in a similar way. There are two advantages in these varia- 
tions over the other methods. First, there is a slight saving 
of time in that the needle does not follow the turning 
movement of the rods but after adjustment can rotate with 
them and swing back before coming to rest. Second, 
there is the by no means small advantage that the needle 
is always ready for measurement and cannot be thrown off 
through unavoidable thrusts on the pin. Unintentional 
freeing of the needle is absolutely impossible, since the 
rinsing current is suited as long as the wider openings 0, 
are free and should a throttling of the passage through 
0, occur the piston k will soon be influenced. Such a 
throttling, however, cannot occur if the outer tube is 
raised. 

^ German Patent No. 168,596; also Osterr. Z. Berg-Hiittenw., No. 43, p. 
561, 1906. 



CORE ORIENTATION 73 

The instrument can also be so constructed that the needle 
is not freed by the relative displacement of the two tubes 
Ri and Ri but by an improved water lead in which a valve 
is closed under the pressure of a spring. The valve spring 
is so adjusted that the valve stays open with the normal 
rinsing current and will only shut on an increase in the speed 
of the rinsing pump. 

The same objections apply in the main here as to the 
apparatus of Gothan with respect to core fractures, etc. 

Lapp's Device. — This simple apparatus was invented in 
1906 by Heinrich Lapp of the well-known firm of deep 
borers in Ascherleben, Germany. The simple principle 
shown in Figs. 38, and 39 has been adopted since in numer- 
ous devices. Figure 38 shows a longitudinal section^ of 
this core orientator with two horizontal sections below. 
It consists of a cylinder a of suitable dimensions made in 
two halves, the lower one fitting over the core in the hole. 
Under the magnetic needle 6, which is borne on a spring 
spindle bearing c, is a plate d of soft material. The needle 
has a lower side pricker e. Above the needle on a rod i 
is a plunger / carried through a shear pin h and having a 
ring buffer g at its bottom end. 

On the rods being lowered and the bottom of the cylinder 
fitting over the core stub, the plunger/ descends by its own 
weight, or by the rod action, and buffer g presses the needle 
down, making an imprint of e in the soft plate d and holding 
the needle in its position of rest. The shearing pin h 
prevents any turning and the lug k with the peg k' in the 
housing a serves for correctly adjusting the housing in the 
core tube. 

The device suffers from the usual defects of this type 
of apparatus, i.e., cavings, poor cores in friable strata, 
turning shocks, etc. Compare Hillmer's deviation and 
dip measuring apparatus made by the same firm and dealt 
with later on. 

Koemer's Core Orientation Apparatus. — This apparatus 
was invented in 1907 by a German engineer, G. Koerner, 

1 German Patent No. 171,349, May 25, 1906. 



74 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



of Nordhausen. It is essentially a double-gimbaled pendu- 
lum apparatus. It is screwed to the upper part of the core 
box and carries indicating needles which are fixed in posi- 





FiGS. 38 and 39. — Lapp's core 
orientator. 




Fig. 40. — Koerner's core orientating 
apparatus. 



tion by dropping in a weight and releasing a fixing device 
which forces pointers into a cork disc. Like his deviation 
device, it shows the dip in amount better than direction, 
the latter being obtained by computation. The pipe drill 
and core barrel are orientated out of the well by measuring 
each stand. Figure 40 shows the apparatus for aligning 



CORE ORIENTATION 75 

the cores on the surface. To the upper portion of the core 
box a screwed to the boring rods h is secured a plate holding 
a pipe c, which leaves a space between it and the walls of 
the core box for rinsing water. In the center of c are oscil- 
lating needles d and e supported on their respective gimbals 
or universal suspensions / and g. Gimbals g are weighted 
on one side by weight h, causing e to incline. Above d 
and below e are cork pistons i moved by springs j toward 
the needle points of d and e. The cork disc i is held by rod 
k allowing d to oscillate freely and carries an arm lever / 
rotatable about the long axis of the apparatus, the lower 
end of this lever holding another arm m by means of rod c 
to actuate the lower cork plunger i. 

Under the top plunger i is a gunlock trigger-releasing 
device actuated by rod n operating springs j which press 
the cork pistons i against the points of pendulum needles d 
and e. Needle d is used for indicating the dip of the bore- 
hole and e for the lateral deviation due to the action of 
weight h. To facilitate this the cork discs i are faced with 
paper scales on which the needle points prick holes. As 
electric cables can not be introduced into 
the hole during boring, the positions of 
the indicating needles are fixed by a 
messenger weight dropped in releasing the 
above device from n. The movement 
relative to the meridian is taken with 
respect to a mark made on the core 
box. 

In core boring the needles are fixed before wrenching 
off the core; then the core is extracted and the core box 
arranged on the surface in such a manner that it is slightly 
inclined and a definite mark arranged on the meridian. 
The cork pistons i are withdrawn and the needles released, 
taking up a position in accordance with the inclination 
of the core box. After the needles come to rest pistons i 
are again released, and the new position of the needles, in 
which the scale of the apparatus coincides with the merid- 
ian, is recorded. Thus, as shown in 40a, we get the points 




76 DEEP BOREHOLE SURVEYS AND PROBLEMS 

a and b obtained underground to take up the new positions 
a' and b' on the surface. In both cases the parallelogram 
of displacement gives the direction in which weights h have 
dipped plumb needle e ; which directions are shown by lines 
oc and oc', and, since the line is in the meridian, angle coc' 
will be the rotation of the apparatus on extracting the core 
box. If the core is turned with its mark from points c to c' 
it will have its proper geographical position aboveground as 
below. A pendulum may be used instead of the plumb line. 
The chief objections to the appliance are: 

1. Dropped messenger weights are unreliable. 

2. In the mud rotary system the apparatus may fail to 
function. 

3. Much time is taken up in surface orientation. 

4. Many unaccountable turning movements are not 
provided for. 

The apparatus, particularly in respect to the methods of 
aligning the geographical positions above and below ground, 
has been subjected to severe criticism by Dr. Freise^ and 
the engineer, Erlinghagen.^ 

Rapoport's Method. — The idea of this device^ is one 
embodying the former notion of a mold, as in Wolff's 
apparatus. It is very ingenious and though apparently 
unsuited to the conditions of actual practice, in its present 
form, contains the germ of an idea which may be useful to 
investigators and inventors. We have failed to trace any 
literature dealing with its application in the field, but 
believe it should not be disregarded. 

Figure 41 shows the apparatus which consists of a 
cylinder a, let down into the borehole and having an axial 
channel b to which an upper conductor c can be joined for 
compressed air or pressure water. Underneath, channel b 
is closed by a valve d which opens an exit channel e on excess 
of internal pressure. The hollow body a possesses four 
borings / at 90 deg. to one another radially in superposi- 

^ Organ des Verein der Bohrtechniker, 1907. 

2 Gliickauf, p. 737, June 15, 1907. 

3 German Patent No. 172,179. 



CORE ORIENTATION 



77 



tional planes. In each of these, under the pressure of a 
spring, is a movable piston g on rods h carrying on their 
exterior ends hinged movable porcelain heads k. If the 
rod is moved outward by internal pressure these heads 
take a mold of the borehole walls. A compass n whose 
needle m is arrestable by the lever o actuated by the spring 
p is used for taking the strata strike. There is a piston con- 
nected to which, as a result of the pressure of spring p, can 




■^ 



Fig. 41. — Rapoport's device. 

close a duct leading to the channel h. The piston is pressed 
up when a means of pressure appears in 6 and the needle is 
freed to take up its position. If before raising the appa- 
ratus out of the hole the pressure channel is closed, the 
piston g goes in first and then q is brought by the spring 
p to the original position, thus again locking the needle. 

Obviously very hard strata, and very friable strata too, 
make the application of the device, in its present form, 
useless ; but, as said, we present the apparatus for its possi- 
ble use under suitable modifications. 

Florin's Method. — This ingenious apparatus was in- 
vented by a chemist, Jean Florin, of Brussels in 1908^ and 

1 Florin, J., Enregistrer rorientation des strates au fond des trous de 
sondage, Annates des mines de Belgique, Tome 13, p. 781, 1908. 



78 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



consists of a photographic device with a lead block base. 
The apparatus was lowered over the core which had been 
previously marked by the trepan and the lead block took 
an impression of the core head while the needle inside was 
photographically checked by special appliances. 

In Fig. 42 it will be seen that no clockwork or other 
complicated mechanism is required, the strong, pressure- 
proof box holding very little movable apparatus. This box 




Fig. 42. — Florin's camera device. 

is filled with water and inside suspended by rubber rings 
is a simple photographic apparatus a. Below this is a 
magnetic needle b, a phosphorescent disc c and an inter- 
changeable lead base d. 

Staggered holes with gratings allow water to penetrate 
to the interior in such a way as to counteract pressure 
effects while preventing foreign bodies from entering. 
Starting at the top we have the photographic apparatus 
in the non-metalhc box in which is a small round and rigid 
celluloid film covered with an emulsion of silver bromide 
in gelatine, very sensitive to light and obtainable at any 



CORE ORIENTATION 79 

chemist's. This film is placed exactly so as to receive the 
image of the needle h and guide marks on the phosphorescent 
disc c below it. The very luminous objective has an 
aperture of /.3 and focal length of about 40 mm. and is 
specially corrected for the refractive index of water; the 
distance from the film is constant. In front of the objec- 
tive is a small shutter plate h which opens only on pressure 
being applied, on a rod projecting externally, when the 
apparatus meets the core. The magnetic needle h is freely 
suspended uncontrolled by any mechanism and is swung so 
as to function even when the apparatus is tilted. Behind 
it is the thin copper disc c covered with a substance insoluble 
in water and containing calcium sulphide. (This is very 
phosphorescent when properly made in the way employed 
for this device.) It has the property of great luminous 
emission. Black guide lines have been traced on the disc. 

A small distance from the above parts is a plate of phos- 
phor bronze sufficiently thick and strong in which are four 
holes of different diameters. These holes serve as guiding 
points and enable one to ascertain whether the lead plate 
has been displaced during the manipulation of the appara- 
tus. Other guiding points enable the bronze plate to be 
set; also all the rest of the movable parts of the device. 
Against the plate is a lead plate for taking the core impres- 
sion on its outside and the impression of the holes on its 
upper face. 

For action the disc is taken out and made very phos- 
phorescent by burning before the surface of the sulphide a few 
centimeters of magnesium ribbon; this strongly excites the 
phosphorescence so that the disc remains luminous enough 
to enable one to read a watch in the dark for 4 or 5 hr. 
This is then screwed back in and the lead plate put on and 
the shutter closed. Now in a dark chamber the sensitive 
film is fixed and the apparatus filled with water and closed 
up, the water being as near as possible in temperature 
to that in the borehole, avoiding air bubbles. This does 
not affect the action of the apparatus at all. The instru- 
ment is now ready to lower into the hole. 



80 DEEP BOREHOLE SURVEYS AND PROBLEMS 

First a trepan is sent down to mark the core head with a 
blow and then raised to allow the apparatus to enter. 
The lead plate d on the base outside takes an impress 
of the core face with its mark. At the same time the lever 
coming into contact with the core uncovers the objective. 
After a few seconds the needle is at rest and overexposure 
of 20 to 30 min. allowed. The image of the needle and the 
guide points is thus fixed on the sensitive plate. The device 
is now raised, an interior spring closing the shutter. At 
the surface the lead plate shows the core-face impress with 
trepan mark on the lower side and the impression of the four 
holes on the other. The film, when developed, shows the 
position of the needle and the guiding marks on the phos- 
phorescent disc. Thus the core is orientated and later 
coring is completed and the core compared. 

The instrument is robust, the lenses of the objective being 
completely isolated in the middle of it and being of great 
thickness are strong enough for the job. It is only nec- 
essary to clean the device carefully after use, the whole 
of the parts, except the needle, being of copper alloy. 

If the borehole water is too hot for normal gelatine the 
film should be plunged into a bath of 5 per cent formalde- 
hyde solution; this makes the gelatine insoluble and capable 
of resisting decay without impairing the sensitiveness 
of the film or the development of the image, which is done 
by a slow process. The phosphorescent plate is designed 
to do away with electric lamps with accumulators which 
are not suitable for shocks. 

The factors operating against the device are the great 
consumption of time in letting in the trepan to mark the core 
and its extraction, etc. Cavings also affect the marking 
and friable strata prevent its employment. If there is no 
orientating coupling it suffers all the defects of any other 
apparatus, giving directions aligned on its own markings. 

Goodman's Core Orientation and Borehole Deflection 
Apparatus. — This device was invented by Professor Good- 
man of Leeds University in 1908 and can be employed 
both for orientating cores and surveying borehole devia- 



CORE ORIENTATION 



81 



tions. It consists essentially of a tube which can be 
fitted over the core stub, the tube containing a hemispheri- 
cal pendulum and clockwork arresting device adjustable to 
a predetermined instant.^ 

In Fig. 43 the hollow cylinder h is shown in the borehole 
a, its prolonged lower part being capable of fitting over the 
core stub with a scratching tooth of steel or diamond for 




Fig. 43. — Goodman's apparatus. 

scribing the same. The hollow pendulum c bearing on 
pivot d on the circular base e is graduated externally on its 
rim Ci and has an agate bearing i for the pivot. The cone 
ends in a short screwed stem g, and a magnet h rests on it. 
The hemispherical screwed cap nut k holds stem g, securing 
the needle h to the top of the cone c. The base plate e is 
borne on a flange of cylinder h and is framed to the upper 
clockwork base plate I by pillars m. On top of nut k a small 
plunger n is provided axially central passing through the 

1 See also British Patent No. 23,003, Apr. 29, 1909. 



82 DEEP BOREHOLE SURVEYS AND PROBLEMS 

upper base plate I. Its lower end ni is enlarged and 
hollowed round to make an all-round contact on the 
hemispherical cap k. A helical spring o about n presses 
under I and against n. The upper end of n passes up 
through lever p which is hinged at q and has a cross pin at 
r to facilitate disengagement of n from k. On releasing p 
the spring o pushes plunger n down on to cap nut k, fixing 
the cone and needle in position. This release is provided 
by the clockwork in frame s by means of flexible wire or 
cord t, from the alarm spindle u. After winding up, the 
alarm is set at any chosen instant for release and in this 
state is lowered into the borehole. When release occurs 
t is unwound from u, freeing spring o and pushing n down, 
thus fixing the cone and magnet in the position in which 
they have come to rest. The hermetical seal is completed 
by means of the cap piece w. Other mechanical or electrical 
means for release may be adopted. 

The magnet is secured so that its center line lies in the 
central plane of the cone passing through the to 180-deg. 
mark. A gage is used to get the inclination of the highest 
and lowest points of the rim base of the cone above the base 
plate e, and the graduations give the azimuth. The angle 
of dip is got by the said difference of heights divided by 
the base diameter of the cone. 

The scribers 4 at the foot of the tube are for marking 
the core by raising and lowering the tube. Then when 
brought to bank the dip of the strata in amount and direc- 
tion can be obtained by noting these marks and the bedding 
Unes, if any. 

The apparatus while strong and reliable, given its peculiar 
conditions of application, has the following disadvantages : 

1. Clockwork mechanism is likely to err under the effects 
of shock on insertion and extraction. 

2. The device has to be separately used to give good 
results; this means much loss of time in changing tools, etc. 

3. If used as a deviation recorder there is no continuous 
record. Each record is a separate insertion and with- 
drawal. 



CORE ORIENTATION 83 

4. If there are no bedding planes visible in the core the 
apparatus is not so acceptable as otherwise. 

5. Friable strata are against its employment as an 
orientator. 

Hall and Armentrout's Gyrostatic Method. — ^This device 
is one of the few known instances of the application of a 
self-contained gyroscopic compass in borehole investigation ; 
most other types have their gyromotors actuated by a 
source of electrical energy aboveground, as will be explained 
in Chap. IX. This apparatus^ has been adopted in the 
California oil fields and is suited for employment with any 
rotary core drill of conventional form. In Fig. 44 it will 
be seen to be mounted on the bracket a on top of the inner 
core barrel 5 in a chambered casing c with closed top d. 
This casing has dividing partitions e and /, housing regis- 
tering elements. 

In the lowermost compartment is a non-magnetic com- 
pass g preferably a gyroscopic compass of the Sperry^ 
type including the conventional frame h having trunnions 
i by which the compass as a unit is supported from the wall 
of the casing c. This compass includes a motor j con- 
stantly driving the sensitive element of the compass, 
the latter being mounted to actuate a dial k disposed upper- 
most of the compass. The motor j is of the alternating- 
current type and current is supplied thereto from an 
alternating-current generator I driven by a direct-current 
motor m with current supplied to the motor from a battery 
n. The dial k has an annular toothed edge adapted to be 
engaged by a dog fixed to the angular extension of rod o 
extending to the cutter bit at the base of the barrel to a 
point between certain of the bits p. Guides q are provided 

1 U. S. Patent No. 1,656,809, Jan. 17, 1928. 

2 British Patents Numbers 15,669/11 for the gyrocompass of E. A. Sperry; 
also Engineering, Vol. 91, p. 816, and Vol. 93, p. 722; Glazebrook, "Diction- 
ary of Apphed Physics," Vol. 4, or T. W. Chalmers, "Gyroscopic Compass," 
pp. 54, et seq., Constable & Co., London, 1920. 

For full mathematical treatment see A. L. Rawlings, "Theory of the 
Gyroscopic Compass and Its Deviations," p. 38, Macmillan & Co., Ltd., 
London, 1929. 



84 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



for the rod to slide in and as the rod p has a sliding fit in 
the tool head its vertical movement causes the dog to engage 
or disengage the teeth on dial k. On 
engaging it locks the dial against rotation 
and it can seat within a groove of a 
stationary rim member of the compass 
frame h securing the arm of rod o from 
lateral movement. Normally the dog is 
urged to engage the teeth by a spring r 
to lock the dial. 

The gyroscopic compass possesses the 
feature of indicating the astronomical 
north direction regardless of the proxim- 
ity of magnetic masses and similar 
disturbances. This feature will be more 
fully described in Chap. IX. 

In operation, the core drill rotates 
continuously in one direction to form 
the core s, and, with the drill in drilling 
position the projecting lower end of the 
rod being in contact with the bottom 
of the well, holds the rod in elevated 
position against the action of the spring 
r to retain the dog out of engagement 
with the dial k. After the core has been 
completely formed the drill is brought to 
rest, after the lapse of a few seconds, 
during which the sensitive element of 
the compass can function to actuate the 
dial k so as to indicate due north. 

It will be seen that on raising the drill 
Fig 44— The Hall- ^^'oi^i the Well the lower end of rod o is 
Armentrout gyrostatic. pulled out of coutact with the Well base 

core orientator. .... . ,„ ,. ,,, , 

pernuttmg sprmg r to function and the dog 
to lock the dial. This gives the direction. The core drill is 
now taken out, care being taken not to turn the drill pipe 
or disturb the recording elements by shocks and bumps. 
The sleeve t is unscrewed from drill head u keeping the latter 




CORE ORIENTATION 85 

stationary and the pipe lifted from the attachment. Door 
V permits access to the gyroscope compartment. The 
direction of the core is read from the north indication 
of the compass. 

The apparatus to be quite successful should have some 
form of orientating coupling. The amount of inclination 
being obtained directly from the core and frame dips, an 
additional dip measurer for the barrel itself should be 
provided to check the absolute core dip. This because a 
fixed gimbaled gyrocompass is by no means as reliable in 
dip readings as one slung from a buoyant ring in an annulus 
of mercury. 

Dixon's Apparatus. — A. F. Dixon and D. Upham of New 
York first invented this device in 1924,^ and it is essentially 
a core orientating appliance. Its chief parts are a base 
core-marking tool, an index sheet or card rotatable relative 
to the tool holder, its position in azimuth controlled by a 
gyrocompass, and a marking device for obtaining the sheet 
position. 

Figures 1 and 2 (Plate V) are vertical sections of one form 
of the device, it being noted that there are several possible 
forms, according as the gyrocompass is in the apparatus 
or a surface master gyrocompass is used connected down the 
hole by wires to a ''repeater motor" lowered into the hole 
with the index sheet, marking device and tool. Consider 
the form of construction shown in Fig. 1 where we have a 
bipartite cylindrical casing, the top part A of which is the 
compass chamber and the bottom B is the tool holder 
screwed on watertight. A cable w conducts current 
to the gyroscopic compass C which is freely suspended 
and carries a sheet or card S. Below S a marking device 
M is mounted on top of chamber B and actuated by the 
electromagnet E so that when the latter is momentarily 
energized by a brief current impulse the marker is rocked 
and pricks sheet S. The electromagnet circuit x may be 
closed at will by switch sinB. The cable wires y supply 
current to the B chamber electromotor P and can be 

1 U. S. Patent No. 1,130,694, May 31, 1927. 



86 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



closed by switch s'. Motor P drives drill D through gear- 
ing train G. When the apparatus is lowered into the hole 
and the drill point strikes the bottom, the drill is pushed 




Plate V. — Dixon's gyrostatic core orientator. 

up and collar U closes the motor switch s' starting the motor 
and driving the drill. 

Shortly afterward collar V closes switch s in the circuit 
of the electromagnet E causing pricker M to mark sheet 



CORE ORIENTATION 87 

S. Collar U keeps switch s' closed until the hoisting 
apparatus allows the drill to drop again. The drill shank 
is not packed to keep out pressure water; the chamber B 
is flooded with water unless previously filled with petroleum, 
glycerine or other non-corrosive fluid. The switch box is 
usually oil filled. Figure 2 is a modification of Fig. 1 
wherein corresponding members are the same and are 
lettered alike with unit indexes, except that the sheet 
marker M' is here a stylus mounted on a carriage moved on 
a track M^ by chain M^ from drum Af^ of clockwork Z 
for timing M'. This clock also closes switch Z^ by arm Z' 
of the motor circuit; otherwise a surface switch is used. 
The track M^ is parallel to the radius of the index sheet S' 
part of the way, and while the stylus carriage is traveling 
on this part of the track the stylus marks the sheet. 

Before lowering from the surface the clockwork is wound 
up and set to close nlotor switch Z' at a known time and 
then rotate drum M^ for moving the stylus. On gaining 
the bottom of the hole the motor starts and the tool 
indents the rock and the mark position will depend on the 
twisting of the device on lowering. After this the sheet- 
marking device operates and marks the index sheet. 
The position of the marking device depends on that 
of the tool, but the position of the sheet is governed by the 
compass. After marking the sheet and rock the whole 
is raised to bank, a coring apparatus is lowered and a core 
extracted with the said indentation on it. This mark is 
correlated with the index sheet mark and the direction of 
dip ascertained. The objections to the device are the addi- 
tional coring operations, dangers of cavings spoiling mark- 
ings, the great consumption of time and therefore money 
and the diameter limitations for all such devices as pre- 
viously noted. 

Hanna's Apparatus. — This device which is essentially 
a compass and plumb-bob apparatus has been fairly exten- 
sively employed in the California oil fields, the inventor 
having been formerly assignor to the Associated Oil 
Company of San Francisco. The compass and plumb bob 



88 DEEP BOREHOLE SURVEYS AND PROBLEMS 

are controlled by the inertia of a heavy rotating mass the 
rotational speed of which does not coincide with that of 
the rods, the resulting momentum difference being har- 
nessed. Figure 1 (Plate VI) shows ^ the position of the 
apparatus capsule 7 relative to the boring bit 2 the core 6 
and the rod string 4. It is filled with a non-corrosive liquid 
like petroleum to counteract pressure. Figure 2 is an 
enlarged view of the mechanism with Figs. 3 and 4 cross- 
sectional views of the same on lines 3, 3 and 4, 4, respectively. 

The compass needle is automatically locked at a pre- 
determined time after drilling ceases, and before breaking 
off the core, as also is the plumb bob, thus giving direction 
and amount of dip. 

The capsule 7 (Fig. 1) is made of non-magnetic material 
as also is the portion of rod string near it, and it is supported 
by fasteners 8 (Fig. 2) to the inner surface of the rod string. 
It has a removable cap 9, for access and inspection, and an 
eye suspension ring 10. The compass 11 may be either 
of the magnetic type (as here) or gyroscopic, and from it 
hangs the plumb bob 12. The compass needle 14 is held 
by a locking rod 15 passing through the compass case 
16 while the plumb bob can be locked by the reticulated disc 
or wire screen 17 engaging its pointed end 13. 

The locking mechanism for compass and bob is a spring 
motor 18 on frame 19 inside the capsule. The spring-driven 
shaft 20 of this motor is connected to a train of gears 22 
(Fig. 3) with a fan-type governor 23, and a double-cam 
24 provides the vertical reciprocation of the compass 
locking rod 15. The plumb bob locking member 17 is also 
mounted on compass-locking rod 15 by set screws 28 and 
both locking devices are arranged so as only to move freely 
vertically. The ratchet wheel 31 and its pawl 32 on shaft 
20 are the starting and stopping mechanism operating 
through the arm 34 and spring 35. The most ingenious 
part of the apparatus is the means for automatically 
starting and stopping the spring motor at the proper time 
with relation to the drilling operation. For this purpose 

1 U. S. Patent No. 1,665,058, Apr. 3, 1928. 



CORE ORIENTATION 



89 



an inertia motor is adopted. This is a heavy solid lead 
rotor 36 on a vertical shaft 37 suitably borne in bearings 
38 and 39. It is so made that it will lag behind the rotation 




FiG.l 



Plate VI. — Hanna's inertia-rotor apparatus. 



speed of the drill, thus continuing to rotate some time after 
the latter, owing to its momentum. On shaft 37 a worm 
gear 40 is engaged by a toothed projection 41 on a verti- 
cally movable rod 42 supported in frame 19. As worm 
gear 40 rotates, with respect to rod 42 and its lug 41, rod 42 



90 DEEP BOREHOLE SURVEYS AND PROBLEMS 

is caused to move up and down. The vertical travel of 
rod 42 is controlled by a light compression spring 43 and a 
collar 44 engaging lug 41. The attached setting rod 45 
with a V kink 46 and angle bend stopper 47 moves also 
vertically upward or downward, and when the V bend 46 
encounters the detent arm it moves it out, disengaging 
governor 23. Thus the inertia motor and associated 
mechanism provide for starting and stopping the spring 
motor. 

For operating the device the capsule is sunk into the hole 
to the position shown by 7 (Fig. 1) with respect to the core 
and when coring commences both compass and bob are 
locked and the mechanism is in the position shown in Fig. 
2. Owing to the inherent inertia of the motor it does 
not turn until the rods have rotated several turns. Thus 
lug 41 gets a planetary movement about the worm, moving 
downward on it before the rotor starts to turn. In this 
way rod 42 moves down the V kink 46, engages and moves 
out detent arm 34 clear of governor 23 and the spring motor 
operates shaft 20 through a quarter clockwise turn. Then 
by the attached mechanism described the compass is freed 
and the plumb bob and their locking bars held clear. 

When drilling ceases the rotation of the worm gear rela- 
tive to the tooth 41 takes place, for then the momentum 
of the inertia rotor 36 is such that it continues to rotate 
after the drilling action ceases when the worm gear moves 
tooth 41 and rod 42 upward. The mechanism may be 
timed for 20 to 30 sec. after the drill stops, when the V 
part of rod 45 will have moved up engaging the detent arm 
34, allowing the spring motor to act. This action of the 
spring motor now moves the stud 25 upward, compressing 
spring 26 and locking the compass needle 14, and at the 
same time the grid disc 17 locks the now quiescent plumb 
bob in position. Thus we get the direction and amount 
of core dip. Cover 9 is removed at the surface and the 
inner mechanism taken out after noting the compass 
orientation marks on the case. The spring shown dotted 
at 48 is then rewound because it operates shaft 20. 



CORE ORIENTATION 



91 



This device has been well tried in California oil wells 
and has yielded reliable results. Its chief drawbacks are 
that for very narrow diameters its mechanism is too com- 
plicated and delicate ; thus it has a critical limiting borehole 
width. It can not be used for the continuous survey of bore- 
holes, being essentially a core-orientating instrument. 
While it does not interfere with the ordinary coring opera- 
tions and requires no special lowering proc- 
ess or apparatus, it is confined to rotary 
boring methods. 

The ingenious notion underlying the 
apparatus is extended in Riemer's apparatus 
wherein the surge effect of an annulus of 
mercury is utilized to produce somewhat 
similar results. 

Macready's Method. — This interesting 
modern method was devised by George A. 
Macready of Los Angeles and can be utilized 
at depths exceeding 6,000 ft., though 



ooo 



Fig. 45. Fig. 45a. 

Fig. 45. — Borehole apparatus records. {By the courtesy of George A. 
Macready.) 

Fig. 45a. — Types of compass pendulum photographs. 

the greatest run to date is only 3,780 ft. It has been devel- 
oped and employed in the Trinidad asphalt deposits, the 
Venezuelan petroleum fields and the western oil areas of 
America. It is suited to holes of fairly small diameter. 



92 DEEP BOREHOLE SURVEYS AND PROBLEMS 

It is essentially a multiple-photograph orientation appara- 
tus consisting of a pendulum and compass device, the posi- 
tions of which are recorded on a long strip (Fig. 45).^ 
The drill rod is orientated by external joint scribing at 
every 10 ft. and aligned on a surface reference mark. 
Photography was chosen as the azimuth recording medium 
because then the pendulum and compass needle can swing 
freely during recording, the photograph automatically 
averaging the mean point about which swing, if any, 
occurs. The recording instrument^ is inside the inner barrel 
to minimize relative displacement from the core. The 
record is of the nature shown in Figs. 45 and 45a. The most 
recent development of this apparatus (Figs. 46, 46a) ^ 
has a long photographic strip on a reel which records 
the position of the pendulum and compass needle at regular 
intervals, thus permitting a complete survey of the well 
and allowing for records of several positions of the core 
barrel during coring. In interpreting a record it will be 
observed that the white lozenge-shaped shadow of the 
magnetic compass card is eccentric to the large dark 
circle of the exposure. The amount of eccentricity meas- 
ures the deviation of the hole from vertical at each exposure 
because the eccentricity is caused by the compass being 
suspended as a pendulum. The inner core barrel is marked 
(and it may also mark the core) and is attached to the 
instrument in a recorded position so that the relative 
positions of core and record are fixed and known. The 
inner core barrel is swiveled inside the outer barrel. The 
outer core barrel is rotated by drill pipe or drill rod to cut 
around a core and the inner barrel is forced longitudinally 
over the core and at the same time shaves the core a frac- 
tion of an inch smaller so that the inner barrel takes a firm 
friction hold on the core. A spring on the inner barrel 

^ From a private communication. 

2 Macready, G. a., Orientation of Cores, Bull. Amer. Assoc. Petroleum 
Geol, p. 571, 1930. 

^ By the courtesy of the Bulletin of the American Association of Petroleum 
Geologists. 



CORE ORIENTATION 



93 



is 
1 




■t 


3R 


t 


-^ ' 


« 
' I 


2 ' 


E 


S > 


1 


1 


1 


pf 


1! 


1 


(i 


ISp 


J 


m 
^ 


.^ 


3 


' --- ~'~fi^^^B 


j^mtk ^^^K^^^^ ■ 










A.P.I. Drill- Pipe Thread 
Upper Sub (Sfeel) 



Fig. 46. — Macready's multiple- 
photograph orientation instru- 
ment. 



Thrust Bearing 

Ouier Case(Non-Magnefic Alloy) 

Insfrumeni Case 
Oraduafed Reference Plug 
Compensafor 

Check Valve 

Coupling CAIloy Sieel) 

Ouier Barrel (Sfeel Drill Pipe) 
Inner Barrel (Sfeel) 



Lower Sub (A Hoy Sfeel) 
Cuffer Head 
Inner Nose 

Fig. 46a. — Assembly of Macready 
orientation core drill. 



94 DEEP BOREHOLE SURVEYS AND PROBLEMS 

holds the inner barrel firmly on the core at all times, so that 
the core is not parted if the outer barrel raises up because of 
vibration or chattering. Circulation fluid passes between 
the barrels and discharges at the cutters to provide cooling 
action. Exact dimensions of construction are important 
to secure best results. 

Photographs can be made at 1-, 2-, 4- or 8-min. intervals 
from the time the instrument is set to go into a well. About 
75 exposures can be made (in 4>^ hr. at 4 min. each) so 
that the 4-min. interval is suitable to 6,000 ft. depth. 
Incidentally, the course of the well is surveyed at the same 
time. 



CHAPTER V 
FLUID METHODS OF SURVEYING BOREHOLES 

Introductory Note. — The outline of a fluid in a container 
was the first means by which the deflection of boreholes was 
surveyed in a systematic manner; it is still the most 
widely employed method. 

Present-day plumbing devices are, so far as demands of 
reliability can go, very highly complicated, sensitive to 
injuries, costly and bothersome and also time absorbing 
in their application. Many of them also require numerous 
auxiliary appliances, e.g., special rods. On the other 
hand, the fluid method which we shall describe is cheap, 
simple in construction and needs less special accessory tools 
and thereby is for most purposes satisfactory and reliable. 
The fluid used may be wax, gelatine, hydrofluoric acid, 
copper sulphate, paraffin or any other substance likely to 
leave the outline of its surface on the tube container. 
It depends on the fact that the fluid surface in hollow 
vessels is always horizontal, independent of what position 
the vessel takes up. If, therefore, the position of the sur- 
face is continually known, we may draw exact conclusions 
as to the position of the vessel at any time. We can fix 
this surface position by having a glass flask as the hollow 
vessel and using dilute hydrofluoric acid which has the 
property of etching the glass. The flask about half full 
of acid shows the surface in the inclined position as a 
clear visible ellipse. The action of the acid on the flask 
walls can be accelerated or retarded by altering the strength 
of the acid solution. 

In the older methods a short bottle, as in Fig. 47, was 
suitably enclosed in a protecting cover, half filled with fluid 
and let down into the hole. In the case of an etching acid, 
hke HF, the etching action of the fluid on the glass walls 

95 




96 DEEP BOREHOLE SURVEYS AND PROBLEMS 

can be accelerated by strengthening it. In a straight 
hole this outline is a circle and an ellipse in an inclined hole. 
The angle which the plane of this ellipse forms with the axis 
of the horizontal plane is equal to the angle between the axis 
of the flask and the vertical, i.e., the sought 
angle of deviation (Fig. 47). Let MN be the 
vertical and AB the vessel axis then the angle 
j8 formed between these lines is the required 
deflection angle. In the vertical position of 
the flask the surface is at CD. 

Actually the surface is at EF due to the 
deviation with CD forming the angle 8 
with EG. 
Now § can be solved from 

FG .^. 

tan 5 = ^ (7) 

where FG is the double difference between the highest and 
lowest positions of the fluid surface while EG equals the di- 
ameter. For carrying out the method by means of HF a 
flask half filled with dilute acid is let down to the place 
where we wish to measure the deviation. In modern 
practice a larger tube is used closely fitting the borehole, 
say a core tube, which, however, should not be shorter 
than 15 ft. In a tube of less length or of essentially smaller 
diameter than the borehole we can not assume that the axes 
of the hole and tube coincide or at least any line parallel 
thereto. If, on the contrary, the tube is about 5 m. long 
and its diameter only a few millimeters less than that 
of the hole, the angle between the tube and borehole axes 
will be so small that it may be neglected for practical 
purposes. In order to protect the flask in the tube against 
the pressure of the water column present in the borehole, 
the tube must be made airtight above and below. The 
upper joint has a rod thread and both joints are provided 
with neck and hook flasks, whereby they can be rapidly 
screwed on or off. The airtight joint is absolutely 
necessary because otherwise water would penetrate into 
the tube and at the greater depths the pressure would 



FLUID METHODS OF SURVEYING BOREHOLES 97 

shatter the flask. However, for small depths and pressures 
bottles are still used, and in order to make the filling of the 
flask as convenient as possible choose a flask with a wide 
neck. The flasks used by chemists with ground-in glass 
stoppers suit very well; however, common preserving bottles 
with screw joints can be used. The external diameter 
of the flask should be about 3 to 10 mm. smaller than the 
tube diameter. In order to center the flask therein it is 
wound about with band tape to the suitable thickness. 
It is advisable not to put the flask directly on to the lower 
joint but to interpose between a small cushion or wad. 

The hydrofluoric acid is to be got in the trade in various 
strengths, mostly at 40 per cent acid. This is diluted 
by water down to about 20 per cent, which will give good 
results. Otherwise it is advisable just before the test to 
fill a flask with the fluid and to determine how much time 
is required to get a clearly visible mark at the fluid surface. 
With a 20 per cent acid 15 to 20 min. are usually 
required. 

There is yet to mention the strong etching action of the 
acid, for carrying which it appears advisable to have strong 
leather gloves. Especially should care be exercised in 
taking the vessel out of the borehole, as it may at any time 
occur that it is broken or has been eaten through by the 
acid, which then flows out of the opened joints over the 
hands of the person. The vessel is taken out of the tube 
at the end of the measurement, emptied and the interior 
and exterior rinsed in clear water; its further handling will 
not be dangerous. 

The advantages of fluid methods of borehole surveying 
are: 

1. The apparatus is easily constructed, read and manipu- 
lated. 

2. It is cheap and the parts obtainable anywhere. 

3. It can be employed in boreholes of small diameter. 
The principal disadvantages of the method are : 

1. It does not provide continuous registration in and 
out of the hole. 



98 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



2. With some fluids capillarity effects are harmful to the 
readings, especially in small diameter boreholes. 

3. Turning of the apparatus in the hole either on going 
down or on being raised out nullifies the direction results 
but not the amount results for inclinations. 

4. The centering of these devices is usually neglected. 
Nolten's Method. — The oldest method applying the fluid 

principle is probably that introduced by G. Nolten, a 
district counselor of Dortmund in 1873.^ 
Hydrofluoric acid is used as the fluid which 
eats an outline at its surface on a glass 
cylinder. The direction of the deviation 
is obtained from a clockwork arrested 
magnetic needle in a cylinder fixed to the 
fluid vessel. 

In Fig. 48 is shown the vessel of colorless 
glass having an exactly cut base with per- 
pendicular walls. If the vessel is half filled 
with dilute acid and left about half an hour 
in an inclined position we get the etched 
mark ah (Fig. 49). If we now lay the vessel 
horizontal we get another mark cd. If we 
draw a parallel to dc through a, then in the 
triangle ahf resulting we know sides af and 
hf so that angle haf can be determined. 

In the hole the glass vessel is encased in 
a watertight, sealed measuring cyhn- 
der c. This is connected by a screw 
spindle I to the rods or rope (the whole internal part can 
be extracted from the shell on this spindle). Gutta- 
percha discs a and ai guard the apparatus against concus- 
sion shocks. The top opening of the measuring cylinder 
has three notches 60 deg. apart which are for fitting on 
three corresponding plates X, Y and Z. After putting 
in the plates they are locked fast by a 60-deg. turn. The 
locking screw goes through plate X. On the lowest plate 
Z stands the glass cylinder c which has a fixed graduation 

1 See also Redmatne, R. A. S., Vol. 1, and Pr. Zeitschrift., Vol. 27, p. 176. 








Fig. 48. — Nolten's 
apparatus. 



FLUID METHODS OF SURVEYING BOREHOLES 



99 



of to 100 deg. and a movable circular scale on its base d. 
For a horizontal position c coincides with a vertical line 
etched on d, which must always correspond with the 
0-deg. point of the fixed scale. A rubber plate tightens 
the cover of c with the aid of a pressure screw s and a lead 
cone e. On the center plate Y is the compass / in a glass 
housing, its needle g being arrestable by the lever h when 
the forked end of the lever is pressed upward. This is done 
by means of a spring j which usually holds the lever off 





Fig. 49. 



Fig. 50. 



against its pressure and is disengaged by the clock i. There 
is a to 100-deg. graduation on the top of the compass 
which agrees exactly, in the vertical direction, with the fixed 
100 scale in the base plate Z. The clock hanging on upper 
plate X is set to actuate the arrest about 15 min. after the 
instrument has reached the spot in the hole where the read- 
ing is being taken. Now from the position of the needle 
and marks, as in Figs. 49 and 50, and the graduated base 
plate we can get the deviation direction. We can obtain 
the amount of incUnation by taking the highest and lowest 
points on the line. If the inclination varies as in the case 
of a hole with changing dip direction, we get the deviation 
curves etched sometimes as in Fig. 50. 

The accuracy of the measurements may be enhanced by 
taking a plaster cast of the cylinder and lines and magnify- 
ing them, then measuring with a cathetometer. Without 
the compass the apparatus is not reliable for tests of the 
direction of deflection owing to the effects of capillarity, 
turning of the apparatus and the thickness of the etched 
mark. The apparatus has been tested for water-tightness 
at depths of over 3,000 ft. and has given satisfactory 
results. 



100 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



Among the principal disadvantages of the apparatus are : 

1. In hot strata special cooling devices have to be 
employed and they interfere with the efficiency of the 
method. 

2. In holes varying in direction of deviation and subject 
to concussion of the rods there is the likelihood of there 
being several etched marks which give rise to confusion. 

3. The apparatus can only make intermittent surveys 
and cannot be arranged for continuous reading down the hole. 

Riihland's Apparatus. — This device was invented to 
obviate the confusion of lines arising from several acci- 
dental markings, as under 2 above. ^ In this method a 
colored fluid was let down the hole in a 
special chambered container and means 
provided for emptying the same while 
a magnet was employed to give the 
direction of deviation. 

In Fig. 51 the apparatus will be seen 
to consist of four chambers 1, 2, 3, and 
4 under one another and connected by 
valved orifices. The chamber 3 is made 
of glass and the others of a non-mag- 
netic material. Chambers 2 and 3 can 
be shut off from the others by means of 
the valves Vi and V2. Valve V2 extends by 
a rod a up into chamber 1 where it sup- 
ports a needle n and has a band bi. A 
tube t is screwed about rod a also project- 
ing up into chamber 1 and ending in a 
band 62- Valves wi and V2 are pressed by 
springs Si and S2 and remain fixed on their seats as long as 
the angle arresting hooks Ci and c^ are not actuated by the 
coils di and d2. The induction coils di and d2, of which Ci 
and C2 are cores, when uncharged with current from the line 
leading up to the surface, keep the hooks and therefore 
the valves shut. The two current lines from the coils go 
insulated in the same cable to bank but are completely 

1 German Patent No. 148,068. 




Fig. 51. — Riihland's 
apparatus. 



FLUID METHODS OF SURVEYING BOREHOLES 101 

independent of each other. As soon as valve V2 is opened 
by way of the coil, hook, and rod the needle is arrested 
against a stop head e, chamber 1 is full open and chamber 4 
discharges. A circular scale is etched on the inner wall of 
chamber 3 for measuring the deflection of the colored sur- 
face. The whole apparatus is guided by three skids / and 
these with a base plate strengthen the instrument, guide 
it into the hole and center it. On reaching the spot to be 
investigated in the hole, coil d2 is first excited from the sur- 
face which causes hook c^ to pull up and spring Si opens 
valve Vi to chamber 3. The colored fluid flows in from 
chamber 2 and indicates its position on the walls of 3. 
After about 10 min. coil Ci is similarly operated by excita- 
tion from bank and so opens valve V2 and lets the fluid flow 
out into chamber 4. At the same time the needle is 
arrested. 

Now the apparatus is drawn to bank and the heights 
of the highest and lowest positions of the color line are 
easily read. This with the needle data gives the amount 
and direction of the deviation. Over Nolten's method this 
method has the advantage of certain reading, not confused 
by subsequent readings produced by accidental change of 
direction. Also the line is sharper and as the vessel is not 
injured by the fluid it can be utilized longer. Furthermore, 
the needle is not arrested by clockwork but at the direct 
will of the surface operator and the spherical surface of the 
glass magnifies the reading; it can be arranged to read to 
10 min. of arc with precision verniers. Its disadvantages 
are those of all fluid instruments as stated in the intro- 
ductory note on this section. 

MacGeorge's Clinograph. — In any discussion dealing 
with fluid methods of surveying boreholes prominence 
should be given to the method devised in 1884 by E. F. 
MacGeorge and tested at Sandhurst and Stawell in Victoria, 
Australia. This because the method marked a significant 
advance upon all preceding methods and instituted an 
epoch of research into the problems attendant on borehole 
deflection which is still active. The apparatus will be 



102 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



clear from Figs. 52 to 56 showing the phials, guide tubes 
and clinometer. The phials contain liquid gelatine. Clear 
glass phials (Fig. 52) nearly filled with a hot solution 
of gelatine and each containing a magnetic needle in 
suspension, free to assume the meridian direction, are 
encased in a brass protecting tube, let down to the required 
depth and allowed to remain for several hours until the 




Fig. 52. — Gelatine phials. 



gelatine has set. On withdrawal the phials are replaced 
at the same angle, at which they cooled, by means of the 
congealed surface seen through the sides of the phial; 
this is brought to the horizontal. Revolving the phial 
upon the part where the magnetic needle is seen embedded 
in the gelatine, until the needle is again in the meridian, 
the phial is then in the same position, both as regards 
inclination and azimuth, as it was when its contents con- 
gealed. Thus we get the gradient and bearing of the bore- 
hole at that spot, and these are measured by means of an 
angular instrument constructed by the inventor. The 
mean of the several phials gives a more accurate result. 
By repeating this operation at measured intervals through- 
out the borehole, its course is mapped. 



FLUID METHODS OF SURVEYING BOREHOLES 103 

The Phials or Clinostats. — The construction of these 
can be readily seen in Fig. 52, which shows the position 
of the magnets and plummets while the phials are hot and 
vertical. If inclined, say at an angle of 45 deg., the plum- 
met rods, still vertical, would occupy the then uppermost 
part of their containing spheres, while the magnets, still 
horizontal and free, would rest vertically upon the pivots 
m the then lowest portion of their containing spheres. 
The clinostat is a true cylinder of glass fitting in the brass 
guide tube. At the lower end, the phial has a short 
neck and a bulb, and within the latter a magnetic needle 
is held upright on its pivot by a glass float, in every position 
of the phial. This allows the needle, which is fixed upon 
its ^'peg," to assume the meridian freely at all times 
without touching the sides of the hollow bulb. Passed 
through an airtight cork and screw capsule at the upper 
end is a small glass tube terminating in another bulb 
above, and with its open lower end inserted in a cork 
which enters the lower neck of the phial. This prevents 
the escape of the needle and float already mentioned as 
occupying the lower bulb. The upper bulb contains 
a delicate plummet rod of glass consisting of a fine rod 
terminating in a plumb of solid glass below and in a small 
bulbous float of hollow glass above. It is very carefully 
adjusted to the specific gravity of the solidifying fluid 
in which it, like the magnet, is immersed. Its poise is so 
adjusted as to insure that the rod or shaft shall be truly 
in the perpendicular line, whatever the position of the phial 
and bulb may be. While fluid, the contents of each phial 
(which completely fill both upper and lower hulhs) permit 
the plummet to hang freely vertical in the center of its chamber, 
and allow the needle in the lower bulb to assume the 
magnetic meridian exactly. When the phial is at rest in 
any position from vertical to horizontal, and pointing 
in any bearing as it inclines, the contents sohdify on cooling, 
and by this means hold fast the indicating plummet and 
magnet embedding them in a solid transparent substance. 
The phial then contains within itself an automatic registra- 



104 DEEP BOREHOLE SURVEYS AND PROBLEMS 

tion of the inclination and azimuth at which it set while, 
say, 500 ft. deep in the borehole. It is easy therefore, after 
its withdrawal, to tilt it to the same angle and to the same 
quarter of the compass as before by simply bringing the 
embedded plummet to the vertical, and the needle to the 
meridian. These clinostats are heated, inclosed within 
their brass protecting tubes and lowered by rods on a line to 
the desired spot in the borehole. Their contents are allowed 




Fig. 53. — MacGeorge's clinometer. 

to cool and congeal and are then withdrawn for inspection. 
The phial with its congealed contents is placed in a sheath 
of brass tubing (Fig. 53) attached to a movable arm which 
carries the index of a vertical arc. This sheath corresponds 
with the Y's of a theodolite, and carries the phial firmly 
upon the same principle as these carry the usual telescope. 
The upper bulb of the phial is brought into the field of two 
crossed microscopes, which are carried with the arm round 
the vertical arc ; these are kept truly in the same plane at 
every angle of inclination by a parallel motion. There are 
vertical lines drawn upon the object glass of each micro- 
scope, these being, of course, kept truly vertical by the 



FLUID METHODS OF SURVEYING BOREHOLES 



105 



parallel motion just mentioned. The phial is revolved in its 
sheath, and the arm is moved along the arc by the tangent 
worm, until the embedded plummet is made perpendicular 
from each point of view, or parallel with the vertical lines of 
reference just described, as viewed through the two cross 
telescopes. The phial is now at the same angle of inclina- 
tion at which its contents solidified, and its lower bulb will 




Fig. 54. — The Swedish clinometer-goniometer. 

be found nearly in the axis of the revolving arm and an inch 
or more above the center of a horizontal circular mirror hav- 
ing a system of parallel lines engraved across its face. 
Reflected in the mirror will be seen the image of the 
embedded needle which pointed north before it was fixed by 
congelation in the borehole. If we now revolve the mirror 
until the 270 deg. of the graduated circle is opposite the 
north (or notched) end of the needle and until the reflected 
image of the needle is sensibly parallel with the engraved 



106 DEEP BOREHOLE SURVEYS AND PROBLEMS 

lines, an index at the side of the graduated mirror frame will 
give the exact angle between the needle and the vertical 
plane of revolution of the phial. This is, in fact, the mag- 
netic bearing of the inclined phial and of the borehole which 
it occupied at the time of the application of the test. The 
same operation is repeated with the other phials which com- 
plete the set, and then the results are combined and the mean 
taken in the same manner as if six separate determinations 
of the same horizontal angle and azimuth had been made 
with a theodolite or an altazimuth instrument. These six 
phials — or self-registering compass clinometers as they may 
be termed — are encased within, and protected by, the 
cylinder or guide tube. 

Figure 54 shows the more modern clinometer-goniometer 
now being used in the Swedish iron fields. 

Cylinder or Guide Tube. — This is a strong brass tube, 
about 6 ft. in length, into which the phials accurately fit 
(see Fig. 55 which shows part of its upper end with the 
phials in their brass slide in the act of entering). This 
tube or cylinder is securely closed against the heaviest 
water pressure likely to be encountered even in bores of 
2,000 ft. depth the glass clinostats being too fragile to bear 
exposure, unprotected, to such a pressure. The guide 
tube is passed down the bore by means of J^-in. diameter 
service piping jointed in measured lengths, the effect of the 
iron being kept from the magnets by the interposition of a 
distance tube of brass. For use in hot strata, where cold 
water must be poured down this small piping in order to 
cool the cylinder below, the upper part of this is pierced 
with holes out of which the cooling stream from the tubing 
may issue and flow down the outside of the cylinder, thus 
congealing its contents. Where the bore is approximately 
perpendicular and the strata comparatively cool, these 
may be dispensed with, and the bore surveyed by lowering 
the guide tube with a small wire rope. Figure 56 shows an 
actual survey of a 500-ft. borehole by this method at 
Stawell, Victoria, in the early eighties. The principle 
of this apparatus is still widely used. The apparatus itself 



FLUID METHODS OF SURVEYING BOREHOLES 107 

is now largely of historic interest, the chief demerits 
accounting for its disuse being 

a. It does not provide a continuous record on insertion 
right down the borehole, the total of many individual 



± 



Upper ; 
Shafi- 1 
Depfh^ 
foTop 




-400 ft 



SOO-ff. 



'Error 75 ff. 
on depth deflection 



Fig. 55. — MacGeorge's guide tube. Fig. 



56. — A borehole survey by 
MacGeorge. 



insertions having to be grouped for the final reading. 
This is tedious, time-wasting and costly. 

b. It fails in magnetic strata and steel-cased boreholes. 



108 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



Maas Method: Hydrofluoric Acid with Gelatine. — 
In this method a small glass tube about 6 in. long by a little 



GELATINE 



THERMOS 
CASING 




Fig. 58. — Two-circle goniometer to measure inclination and direction o-f drill 
holes. {After E. E. White.) 

over 1 in. in bore is used. It holds HF in one end and has 
gelatine in the other holding a small compass. To obviate 



FLUID METHODS OF SURVEYING BOREHOLES 109 

the danger of premature solidifying of the gelatine in holes 
of great depth, with the consequent fixing of the floating 
needle, a small thermos flask (Fig. 57) is used to hold the 
gelatine and needle, the other half of the apparatus having 
the tube of HF. Figure 58 shows the special goniometer 
used for checking the results. The Maas method used to 
be popular in the Lake Superior mining fields years ago. 
The method is fully described and illustrated by E. E. 
White. 1 

The Modified Maas Method.— In the modern adapta- 
tion of Maas' method HF with either gelatine or paraffin 
wax is used. If either of the latter is adopted it is melted 
in the hole after lowering the instrument.- This obviates 
the thermos flask trouble of Maas and MacGeorge. 

The apparatus a (Fig. 59) is let down on a cable b which 
carries a connection c to a dynamo aboveground. An arc 
d in the circuit is carried through the casing, with the glass 
vessel e inside, and when in position the current is switched 
on and the wax or gelatine / melted, giving about three- 
quarters of the container length of fluid. In this thinned 
state it has a horizontal surface and the magnet of the com- 
pass g enclosed in the very mobile liquid can easily move, 
as seen in Fig. 59. After a given time the current is 
switched off, the paraffin again solidifies and the apparatus 
is withdrawn. The amount and direction of deviation 
are now easily read. 

The apparatus is widely used today owing to its simplic- 
ity, cheapness and reliability for most purposes. It has 
been well tried in South Africa. 

Meine's Apparatus. — As a variation of the principle of 
using a fluid for marking (just for the time of the survey) 
the position of its surface in a vessel. Dr. F. Meine of 
Berlin produced the device^ of Fig. 60. In effect it con- 
sists of a body being automatically immersed in a fluid 

1 Bull. Amer. Inst. Min. Eng., No. 71, p. 1277, 1912. 

2 Fauck, a., Remarks at the November, 1910, Convention of Austrian 
Mining Engineers and Architects, Organ des Verein der Bohrtechniker, p. 277, 
Nov. 20, 1910. 

3 German Patent No. 157,879. 



110 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



at a definite instant and drawing the same out. The 
immersion and extraction are effected by clockwork, which 
at the same time actuates the arrest of a magnetic needle. 
In Fig. 60 the casing may be screwed off into two parts 
a and h, and they are separated by a cross floor c. In the 
upper part are the motion apparatus and the immersion 




FIT 



:^^p, 



Fig. 59. 



Fig. 60. — Meine's apparatus. 



body. The lower part is filled with an etching or coloring 
fluid. The clockwork E stands on plate P which is sup- 
ported on three legs d, and on the upper cover plate of the 
clockwork a strap S carries a magnetic needle N. The 
spring of the clockwork moves a drive of three gear wheels 
i, ii and 12 and a toothed rack is which carries the immersion 
body. This arrangement causes the rack either to descend 



FLUID METHODS OF SURVEYING BOREHOLES 111 

with the immersion body or to pull it out of the fluid. This 
is done by automatic switching for the drive ii 12- The 
material of the body immersed may be altered to suit the 
fluid being used, and this latter may be etching or coloring. 
With colored fluid the curves can be indicated direct on to 
paper. 

On taking a measurement the clockwork is adjusted so 
that the needle is clamped about 10 min. after entry 
into the hole. After this arrest, the body is immersed 
in the fluid for about 2 min. and is then raised out of it 
automatically. Since the motions can be easily fixed 
beforehand aboveground, one is informed as to how much 
time is required for effecting complete marking. 

The apparatus has the advantage of great simplicity in 
construction and manipulation. Even if the measurements 
are restricted to a definite time and the apparatus must 
be let down anew for each reading, there is the advantage 
that after once adjusting the mechanism everything is 
automatically controlled without special attention on the 
part of the people attending the device. Again to be 
able to indicate the position of the fluid surface directly 
on to a paper will, in many cases, be most convenient and 
of advantage in the evaluation of test results by computation 
or graphically. The measurements need not be dependent 
on a time interval for operation; an electromagnet, surface 
operated, might be used to arrest the spring. The usual 
demerits of fluid methods, i.e., single readings, capillarity, 
etc., hold, but the great defect of the method is the lack 
of a centering device. 

Any method which gives the direction of deviation in 
the hole is unacceptable if it has no device, as, say, in 
Erlinghagen's apparatus, to prevent turning of the hole 
on insertion or extraction, or some other means of showing 
the direction in situ. 

Macfarlane's Apparatus. — G. C. Macfarlane's apparatus 
was probably the first that utihzed the electric current 
and galvanometer which appears such an important feature 
in subsequent inventions. He measured the electric cur- 



112 



DEEP BOREHOLE SURVEYS AND PROBLEMS 




rent variation in resistance wires which dipped into a bath 
of mercury, the immersion of^ the wires deciding the 
resistance. The direction of the deviation was obtained 
at the same time by a freed needle. Two steel cylinders 
a and b (Fig. 61) are assembled, b inside a, with a fitting 
closely in the borehole and with b fixed to the boring rods. 
The lower part is filled with mercury which, when the 
apparatus is in the perpendicular position, 
reaches up to the lower edge e of the upper- 
most of the two insulated strips e and /. 
Another insulated strip is at g. The iron 
wires h and hi are insulated down to a short 
distance (about 1 in.) over the mercury and 
joined together in a copper wire i which 
goes through the rods to bank where it is 
connected to a tangent galvanometer and 
battery. 

If we now turn the rods slowly in a hole 
deviating from the perpendicular, the thin 
piece of wire k, between e and /, emerges 
partially from the mercury. In this way 
the resistance to the passage of current will be increased 
and accordingly the deflection of the galvanometer will 
be diminished. When this deflection has reached a mini- 
mum, e and g lie in the plane of greatest inclination of the 
borehole. 

From the difference between the maximum and minimum 
throws of the galvanometer we may determine, once for 
all, what resistance a given length of wire k offers and so 
get the inclined position of the hole. A rubber boat I 
floats on the mercury carrying a magnetic needle. This 
float is guided by rods mm. The hard rubber ring R stand- 
ing up on two points at about 90 deg. to the piece of wire 
k is horizontal if e, f and g lie in the plane of greatest inclina- 
tion of the hole. A steel wire encircles the lower side of R 
and is intersected by e and / at opposite places and is 

^See also Redmayne, R. A. S., "Modern Practice in Mining," Vol. 1, p. 
177, and F. Freise, "Stratameter," p. 43, 1906. 



Fig. 61. — Macfar- 
lane's apparatus. 



FLUID METHODS OF SURVEYING BOREHOLES 113 

in connection with the supply current from the surface. 
The wire n is fastened to a pin. In the normal position 
the mercury presses the needle against the compass 
ring. The south pole of the needle is insulated, thus a 
current through n and hi must pass through the north pole. 
As soon as the dip is fixed, a pressure of air is blown on to the 
surface of the mercury, freeing the needle. When the 
pressure is taken off the needle settles. Now n and hi are 
connected to the galvanometer and battery and the direction 
of dip determined by noting that the deflection of the galva- 
nometer is inversely proportional to the deflection of the 
north pole, which information is provided by the opposite 
points e and /. The demerits of the device lie in the steel 
casing and air pressure interfering with the needle; still 
the method is the forerunner of several continuous register- 
ing devices using the same principle. Variations, to the 
benefit of the device, will immediately suggest themselves, 
such as non-metallic casings and insulating the pin to the 
core of an electromagnet. 

The Kiruna Method. — This is an electrolytic precipita- 
tion method devised by the Swedish Diamond Drilling 
Company with the assistance of the Jernkontoret — the 
Swedish Iron and Steel Society — and is named after the 
famous South Sweden iron field where it was first employed. 
Prof. Walfrid Petersson of the Royal Mining School, Stock- 
holm, completed the analysis of the method. 

As previously discussed, the elliptic outline of a fluid in 
an inclined container determines the dip angle, and the 
major axis of it the direction of this dip. If two such 
containers are rigidly connected a distance apart, the form 
of the resulting ellipses and their major axes will fully 
decide the dip in amount and direction. Certain terms 
are necessary to a mathematical comprehension of the 
principles involved, thus:^ 



1 Peteksson, W., Metoder for Matning av Avvikelser i DjupborrhS,!, Jern- 
kontorets Annaler, pp. 224-262, 1922; also Eng. Min. Jour. Press, Vol. 117, 
No. 17, Apr. 26, 1924. 



114 DEEP BOREHOLE SURVEYS AND PROBLEMS 

The zenith angle or angle between the borehole axis at 
a given point and the vertical = 6. 

The apsidal plane or vertical plane containing the major 
axis of the ellipse. 

The north angle or angle made by the section of the apsidal 
plane with the horizontal and measured from the true 
north = a. 

The apsidal angle or angle between the apsidal plane and 
the plane through the borehole centrum and a generatrix 
scribed on the lining = \p. 

The relation between the variations of the north angle 
Aa and those of the apsidal angle Ai/' is 

Aa = Ai///cos 9 (8) 

Thus it is possible to survey drill holes, for the change 
of the north angle can be calculated from point to point 
after the angles 6 and \p have been measured. Thus the 
positions of the tangents to the center line of the hole are 
obtained at a number of points and the course of the hole 
can be determined approximately by calculating the open 
traverse of which these tangents are component parts. 
The angles are determined by electrolytic registration. 
This is done by sinking a cylindrical vessel containing a 
galvanic bath down the hole and precipitating a metallic 
coating on a cathode immersed in the bath. The outline 
of this coating shows the position of the cathode in relation 
to the horizontal plane and if the cathode is of cylindrical 
form we get either a circle or an ellipse. 

Figure 62 shows the registering device consisting of the 
electrolytic vessel A and the anode connected with it, 
the electrolyte (CUSO4) and the cathode B which is a 
carefully polished glided copper cylinder on which precipita- 
tion is made. 

The cylindrical glass electrolytic tube has its long axis 
coinciding with that of the hole at the spot to be surveyed. 
The current is supplied from a surface battery through a 
base contact connected with the anode by means of a pin 
through the glass. The thin copper sheet anode (not shown 



FLUID METHODS OF SURVEYING BOREHOLES 



115 



in Fig. 62) closely fits the inside of the glass tube. At the 
top the tube narrows into a neck with a threaded ring 
joining the glass tube with the cathode. 




Fig. 62. 

The registration apparatus is enclosed in a steel tube 
fitting closely in the hole and the registrations are made as 
follows : 

The zenith angle 6 is obtained by noting the greatest 
{h^^J and the least {h^.^J heights of the precipitation on 

Three phnes, ^BC, ACD. and BCD are all af right 
angl&io each other. 

Angle BAC - 0, Angle DAC = ©j 

A plane through A, B and D corresponds to the fluicf 
^surface. 

The line A -£" corresponds to the great axis 
and ihe angle D Ct is the apsidal angle ff> 

Tan V> = -r T- — 

^ "l&O-l-'O 




Fig. 63. 



the cathode cylinder (Fig. 63) and it is found from the 
relation 

h — h 



tan 6 



max ' mm 



d 



(9) 



where d is the diameter of the cathode. 



116 DEEP BOREHOLE SURVEYS AND PROBLEMS 

The apsidal angle yp is found by measuring the precipita- 
tion heights at four generatrixes 90 deg. from each other, 
beginning at the one to which the apsidal angle refers. 
The heights found in this way are 

ho, hgo, hiso, hiiQ 

from which we get two zenith angles, dx and 62, showing 
the dip of the elliptical surface of the fluid in two directions 
at right angles to one another:^ 

, ^ ^180 — ho /i27o — ho , , 

tan di = - — -J ; tan 62 = ^ (10) 

Knowing now di and 62, the direction of the major axis of the 
eUipse is also known. 

The precipitation heights are measured by aid of a special 
microscope with adjustable tube in which is a scale grad- 




FiG. 64. 

uated in tenths of miUimeters (Fig. 64). It is possible to 
determine the angle 6 to as close as 15 min. which is con- 
sidered very satisfactory. 

When determining ^^ less accuracy is to be expected, and 
this accuracy falls off the smaller the zenith angle d, i.e., 
the more vertical the hole. For a zenith angle of 5 deg. the 

1 From some notes kindly supplied by the Swedish Diamond Drilling 

Company. 



FLUID METHODS OF SURVEYING BOREHOLES 117 

average error in \p will be about + 5 deg. and for ^ = 10 deg. 
about + 3 deg. 

The manner of proceeding with a survey depends on the 
accuracy possible in measuring the angle \}y. First get the 
general dip of the hole by lowering an electrolytic registering 
apparatus on a steel wire and measuring 6 at every 250 
ft. or thereabouts. 

1. If 6 is at least 15 deg. the accuracy in measuring \p 
will be such that we may proceed by the method of succes- 
sive bearings, i.e., a string of drill rods 30 to 100 ft. long is 
lowered into the hole. At the end of each is an electrolytic 
registering device and these are rigidly orientated to one 
another by a scribed mark or generatrix on the rods. 
The first registration is made with the upper apparatus 
in the mouth of the hole so that the traverse can be referred 
to a fixed reference mark on the surface. Then the whole 
string is lowered until the upper apparatus is in the position 
formerly occupied by the lower one and a new registration 
is made. In this way the hole is surveyed by successive 
determinations length after length. 

2. If d is less than 15 deg., i.e., the hole is more or less 
vertical, the following method is used because the successive 
bearings method would be risky, since any errors would be 
cumulative and might render the survey void. To prevent 
this, orientation from the surface is used. In this method 
a string of drill rods is let down from the surface and it has 
an externally scribed generatrix. Part of it is kept out 
of the hole for orientating the said mark. Registering sets 
are put in every 200 ft. and also orientated to the mark. 
Instead of this mark it is often found more reliable to have a 
device known as an ''orientating coupling." This coupling 
(Fig. 65) is so made that it does not allow torsion between 
the rods. Ordinary drill rods make up the rod string and 
the joints are pitched and nailed to hold them tight. This, 
with the orientating couplings at each end, keeps the rods 
straight and orientated to the surface reference mark. 

When the rod string and apparatuses have been lowered 
into the hole the current from a surface battery is switched 



118 DEEP BOREHOLE SURVEYS AND PROBLEMS 

on and passes through an insulated copper wire down the 
rods. The anode of the lowest apparatus is connected 
to the rod string. 

In order to control the manner in which the precipitation 
takes place and to judge the length of time it ought to last, 
it is advisable to shunt in an extra registering apparatus 
visible aboveground. 



Fig. 65. 

When sufficient precipitation is obtained, the rod string 
is removed from the drill hole. The precipitation heights 
on the cathodes are measured and the angles 6 and 
\p calculated from the above formulae. This method 
of surveying with orientation from the surface, however, 
is slow and comparatively a time-consuming work. There- 
fore the method of surveying with successive bearings is 
generally to be preferred, if conditions permit its use. 
In most cases the two methods of procedure are combined. 
For instance, when surveying a hole vertically set, orienta- 
tion from the surface is used down to the point where the 
zenith angle is large enough to allow surveying with succes- 
sive bearings. 

The Kiruna method is intended solely to give information 
as to the courses of drill holes that is sufficiently accurate 
for practical purposes. The Swedish Diamond Drilling 
Company has proved this new method fully. 

Good results have been obtained at Kiruna and in the 
United States with this method. Figure 66 shows several 
of these, including the 1,300-ft. Oskar borehole. The 
designers make no pretensions to the great accuracy 
required in such contracts as freezing shaft holes for 
instance, but guarantee to survey a borehole put down in 



FLUID METHODS OF SURVEYING BOREHOLES 



119 



places where the magnetic needle would be useless. Such 
places are, of course, in iron fields and certain of the basic 



johfL n 




Fig. 66. — Specimen borehole surveys by the Kiruna method. 

igneous rocks. Moreover, good instrumental work can 
be done by the Kiruna method in holes of L4-in. diameter 
after due allowance for cohesion and capillarity has been 



120 DEEP BOREHOLE SURVEYS AND PROBLEMS 

made. Most modern multiple-photograph or gyroscopic 
methods have ceased to be of service long before the hole 
has decreased to such low dimensions, and again this method 
has often stood the test of repeated surveys, perhaps the 
most exacting check a method may face. 



CHAPTER VI 
COMPASS AND PLUMB-BOB METHODS 

Introductory Note. — The magnetic compass as a direc- 
tional agent has been known in the East since time imme- 
morial, coming to Europe in the beginning of this millenium ; 
consequently it is not surprising to find it one of the chief 
deviation measurers in borehole surveying. 

It is a simple and reliable tool even in places of rapidly 
altering declination, since its readings in the borehole 
are more or less directly under the surface station where 
they are being deciphered. In regions of great magnetic 
disturbance, such as the great iron fields of Sweden and 
the United States and also in certain iron-bearing basic 
igneous rocks, it is untrustworthy and misleading. These 
remarks apply also to boreholes which are steel lined to 
spots near the place of its application and to apparatuses 
incorporating any other than non-magnetic material in 
their construction. It is also conceivable that periods of 
magnetic storms and the phases of diurnal and secular 
variation might sensibly affect the accuracy of the magnetic 
needle. 

The plumb bob, on the other hand, is a far more constant 
servant obeying ever the line of gravitational pull which 
does not vary to any measurable degree for our present 
purposes anywhere on the earth. In the short length 
of the longest plummet used in borehole survey work, 
masses of great altitude like the great mountain chains or 
lack of them like the great depths of the sea, in its proximity, 
can not alter its suspension line to any measurable extent. 

One of the earliest uses of the compass in borehole surveys 
in Britain was that adopted by Mr. Haddow at Younger's 
Holywood Brewery, Edinburgh, in 1884. It did much to 
stimulate interest in the compass as a borehole deflection 

121 



122 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



measurer and, crude as it appears, therefore deserves a 
place of regard in our remarks. Here it was decided, 
after the borehole had gone down 200 ft,, to connect it by 
a mine with a neighboring well 18 ft. 3 in. distant, center 
to center. A mining engineer was then sent down, and he 
showed where the hole ought to have been, but as it was 
not to be found at that spot, it was evident that it had 
diverged from the vertical. The ground had already been 
cut away all round the place, and an unsuccessful attempt 
had been made to locate the hole by the device of listening 




,4 = Vertical Base of Borehole 
E=Aciual 

Fig. 67. 



while the rods were shaken within it. Mr. Haddow cut 
a space of 3 ft. all round this spot, and the mine extended 
6 ft. farther before he attempted to indicate the position 
of the hole by the device of passing a magnet down it, and 
noting its effect on a compass stationed in the mine. He 
procured four 8-in. bar magnets, which he put end to end 
and secured between two laths of wood. These were 
lowered into the bore with the south pole downwards. 
The north end of the compass needle moved first to the 
west, then to the east of zero, which showed that the mag- 
nets were on the west side of the compass, and led to the 
mine B being cut (Fig. 67). While this was proceeding 
he set the compass on a table and passed the magnet 
round it; finding a number of points on the floor where the 
deflection of the needle equaled 3^^ deg., he then drew a 
line through the points found. He did the same for other 



COMPASS AND PLUMB-BOB METHODS 123 

deflections and thus produced a series of curves. The com- 
pass was then stationed at the points C and D in the mine 
and the deflections noted. The points CD were marked 
on the plan and a tracing of the magnetic curves set over 
each point as shown. The observed deflection at C was 
3 deg., and at B, Q}4 deg. The bore E was found where 
the curves corresponding to these deflections crossed one 
another, being about 8 ft. from the expected position. 

Although this was a relatively short borehole it well 
illustrates the truth that nearly all boreholes deflect in 
greater or less degree. One has but to lay out a few 
hundred feet of securely jointed drill rods on an uneven 
ground surface to note how easily this virtual wire will 
sag and bend to accommodate itself to the local contour. 

The Otto-Gothan Apparatus.— This is essentially an 
improvement or addition to Gothan's original stratameter 
described in Chap. IV (Plate IV) and the same lettering 
and terms apply in Fig. 68 as there. The addition con- 
sists of a bolt q, which, during the running of the clockwork 
i, is pressed by the end of rod p as a result of the action of 
spring n which actuates the time indicator r. The bolt q 
is pressed against the action of spring c so that the bolt is 
always in contact with another fixed point opposite thereto. 
On these two points a ring t is supported, forming the upper 
end of a plumb line which swings above the disc u of wax 
or any other soft material. The rod p is provided at its 
lower end with a groove or slot z, which, on the arresting 
of the clockwork, is raised by the spring n until the bolt q 
can pass through the slot z, so that the latter is pressed 
out of engagement with the ring t by means of a spring c, 
the plumb line being thereby allowed to fall a short dis- 
tance and to make a mark on the soft material u. 

The magnetic needle I is provided with small pinlike 
projections, which, when the shaft is raised by the turning 
of the cam s, become inserted in a bar or pad m cut from or 
covered with cork, paper, leather or other suitable material, 
and the needle is thus held securely in position until the 
apparatus is brought, for inspection, to the top of the boring 



124 DEEP BOREHOLE SURVEYS AND PROBLEMS 

The whole is enclosed in a casing / capable of being 
hermetically sealed, the casing being secured to a plate e 




Fig. 68. — The Otto-Gothan apparatus. 

screwed into the bore cylinder ab. The indicating device 
can be removed from the casing as a whole by undoing the 
screw. The action of the device is as follows : 



COMPASS AND PLUMB-BOB METHODS 



125 



When a portion of the core of a boring has been broken 
off and removed the apparatus is lowered down into the 
borehole, and when it reaches the bottom the clockwork i 
is arranged to arrest the motion of the magnetic needle I 



a 



c; 



m 



u — u 

Fig. 69. 



Fig. 70. 



and to raise the spring n. The plumb line is thereby 
lowered, a mark is made on the wax or hke disc u, and, 
should the position of the boring tool be inclined, the mark 
is outside the center of the disc. The apparatus is removed 
from the borehole and the direction in which the magnetic 
needle I has been arrested indicates the north and south 



126 DEEP BOREHOLE SURVEYS AND PROBLEMS 

line, and the direction and extent of deviation can be 
ascertained from the mark of the plumb on the disc u. 

The plumbing plate is scored with concentric rings 2 mm. 
apart and has north-south and east-west lines, their inter- 
section being directly under the plumb point of the appara- 
tus when the latter is in the vertical position. The plumb 
takes about 15 min. to come to rest, so that oil is often put 
in the housing to damp the swing to about 2 min. 

The idea is sound and suited to precision work. If its 
application shows only approximate results this is due 
chiefly to magnetic surroundings or to its being impossible 
to set the axis exactly on the borehole axis. 

Figure 69 shows the entire apparatus with its small 
conical tripod legs for fitting to the non-magnetic tube 
shown in Fig. 70. 

Marriott's Instruments. — H. F. Marriott invented his 
well-known borehole survey apparatuses in 1904 and they 
have successfully withstood the severe test of prolonged 
application, particularly in the gold fields of South Africa, 
for many years. He produced two electrical devices: (1) 
a continuously working instrument and (2) an intermit- 
tently working one which sufficed only for single readings 
at individual points being surveyed. 

Marriott's continuously recording instrument for obtaining 
the deflections of a borehole refers particularly to surveying 
the amount of dip,^ not its direction, and is illustrated in 
Fig. 71. Figure 71 shows the modified form of the instru- 
ment which is essentially a method wherein a pendulum 
varies the resistance by a rheostat. 

Here we have three plumbs F pivoted to the vertical rod 
E by the connecting rods /' instead of one plumb, as in 
the earlier design. The strong outside gun-metal casing 
A of the instrument has a hollow brass hemicylinder B 
pivoted truly axially inside it on pins b, h' . The securing 
pivot screw h' in the base disc a' is insulated in an ebony 
bush. So also are the discs h^ and h^ in the ends of B 
insulated. An ebony disc c in the top of tube A carries 

1 Trans. Inst. Min. and Met., Feb. 16, 1905. 



COMPASS AND PLUMB-BOB METHODS 



127 



the contact rings and is screwed to the casing. The 
brackets D, D' inside B carry the vertical rod E with the 
plumb bobs F. These bobs can swing freely in one plane 
only. The plumb-bob system is attached to a switch arm 

G, having a strip of platinum 
on its upper end so that its 
movement causes the arm to 
describe an arc about the pivot 
/. The said strip presses on 
the commutator H carried on 
rod E, which rod also carries the 
resistance coil J connected to H. 
The alternation of conductor and 
non-conductor strips in H causes 
alternations of current and 



/,■ 



n 



Fig. 71. 



ZZvl 





Fig. 72. 



Fig. 73. 



cut-out as the switch arm G moves, as shown in Fig. 72, 
or it may be arranged, as in Fig. 73, to start from a maxi- 
mum resistance and gradually cut out the resistance as 
G moves over H. Or, again, it can be arranged to increase 
the resistance from the minimum according to the inter- 
spacing of the platinum and ebonite segments in the com- 



128 DEEP BOREHOLE SURVEYS AND PROBLEMS 

mutator H. The current is supplied through the wires 
K, L, from a battery of known electric motive force having 
a galvanometer and standard resistance box in the line. 
In this way the declination of the plumb bob is known, and 
therefore, by means of the galvanometer, a calibration 
scale can be constructed. The wire from K is attached 
to the top pivot screw h, and that from L to the hemi- 
cylinder B, and so to F and the switch arm G. 

When the casing A is tilted, the weights M, M, on B, 
cause the latter to revolve on its pivots h, h' and bring it to 
rest in the position in which G moves in a vertical plane. 

The cable is internally screw-threaded into the instrument 
at m by means of the plug N (Fig. 74) having a further 
external thread n' to assist the connection to casing. The 
cable is also secured in the plug by a screw thread n^, 
and a cap Q covers the top, holding the gland nut P with 
its gripping pieces r. 

The instrument is lowered into the hole by a 3^^-in. wire 
rope containing two insulated conductors inside it. These 
lead through the connecting plug of Fig. 74 on the lower 
end, and on the other to contact rings on the sides of the 
surface drum on which the rope is coiled, and through which 
a pair of brushes make contact with the current supply. 
A measuring wheel, over which the rope passes, gives the 
distance down the hole to the apparatus. The surface 
recording instrument is attached at the contact rings, 
and by the galvanometer system of cahbration can be 
arranged to give a continuous record of the variation 
in dip of the hole. This instrument does not record the 
direction of dip. Marriott's second form of this instrument 
records the amount and direction of dip, but, however, 
intermittently. 

Marriott's Intermittently Recording Instrument for Direc- 
tion and Amount of Dip in Deep Boreholes. — Referring to 
Fig. 75 which illustrates the instrument used in this 
method, it will be seen that A is a copper or brass tubular 
vessel having a screw cap B, details of which are shown 
in Figs. 76 and 77. This screws into the upper end of the 



COMPASS AND PLUMB-BOB METHODS 



129 



tube A, while in the lower end is screwed a similar plug 
C washered at E. The wiring connection is similar in 
construction to that previously described above. These 
wires d, d' are carried in two opposite longitudinal grooves 
a^, a^ removing them from the circumference of the tube A 
from which they are insulated (Fig. 75). One wire a^ 
is connected with the terminal G and the other, a^, with the 




Fig. 74. 




terminal H. These terminals G and H are connected 
to the resistance coil J, and projecting well up through 
this coil is a needle K affixed rigidly to the base plug C. 
When assembling the parts, K is screwed in through the base 
by means of the nut k' beneath. Balanced on the point of 
K (Figs. 78, 79) is a magnetic compass L, attached to a 
conical base I. K balances this hollow base inside, and 
horizontally over the needle L lies the mirror M. 

When making a survey, the instrument is lowered into 
the hole by means of the cable hawser to the point at 



130 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



which it is desired to investigate. A strong current is 
passed through the resistance frame J and allowed on for a 
length of time sufficient to enable it to liquefy the wax 
in the tube A. When this is considered accomplished 
the current is cut off, whereupon the magnetic compass L 
assumes the magnetic north and south directions. The wax 
is then allowed to cool and resolidify, after which the instru- 
ment is withdrawn from the hole. 

The direction of dip is obtained by noting the declina- 
tion of the silver mirror M from the horizontal with regard 




Fig. 76. 



Fig. 77. 



Fig. 78. 



Fig. 79 



to the direction of the compass L (Fig. 75). The dip is 
obtained in some forms of this instrument by means of a 
gimbaled dish instead of the plate L, which like the plate 
will become horizontal in whatever position the instrument 
may be placed when the paraffin wax surrounding it is 
melted by the current. A little melted paraffin is also 
poured into the dish or pla.te so as to seal the needle when 
it cools. This separation of the needle from the mass 
of the paraffin prevents the needle from being disturbed 
by the liquefying or solidifying of the paraffin. It is usual 
to fill the space about the coil and outside the dish up to 
the halfway mark, so fixing and warming it. Simple 
protractors may be used for the two fundamental angular 
measurements at the surface. Figure 80 shows plan and 
section of a survey, by these methods, of a borehole on the 
property of the Turf Mines, Ltd., Johannesburg. The 
apparatus, though one of the most reliable instruments of 
its class, is a time consumer in that there is no continuous 
record of both amount and direction of deviation down or 
up the borehole. The first instrument detailed registers 



COMPASS AND PLUMB-BOB METHODS 



131 



only dip in amount continuously and the second, though it 
gives both amount and bearing of dip, is intermittent. 
These are the only drawbacks to this clever device, which is 
independent of torsion in the rods or lowering rope. 



Boifom of Hole 



Surface of Ground 




4165 Esfimafed 
depfh of Reef 
veriiocilly below 
Mouth of Borehole 



Fig. 80. 



Mollmann's Apparatus. — This device,^ invented in Dort- 
mund in 1904, is an improvement on previous pendulum 
or plumb-bob apparatuses in that the vertical position 

1 German Patent No. 155,849, Oct. 22, 1904. 



132 DEEP BOREHOLE SURVEYS AND PROBLEMS 

of the plumb is taken from a pendulum swinging in a definite 
rotatable plane with the aid of a vernier and scale on a 
graduated circular segment. In this way errors in obtain- 
ing the position of the apparatus are either eliminated 
entirely or essentially lessened. Figures 1 to 4 (Plate VII) 
show the interior of Mollmann's apparatus. Through the 
center of the covers h and 5i of housing a (Fig. 1) go two 
screws c and Ci bearing a rotatable fork d. Below cover h 
is a plate / with an attachment e against the one side of 
which presses a spring ^ in a groove (Fig. 4), and this 
presses the portion e against a rod h. This rod h can be 
worked up and down by clockwork from the wheel 2' 
on its prolonged screwed axis k. According to the lift 
of the rod h a lug n under disc / engages, through the bore 
m of disc /, a disc p held by spring pressure. Between the 
discs / and p there is a plate q which is bridged to the fork 
d and can move it up and down in a slit. The plate q 
and its bridge is borne on the upper part of the fork under 
a constant spring pressure by rod r which at its lower end 
lies on the nose y which is likewise spring-pressed against 
lever hi. The latter is connected by lever si to the disc t 
(seen in end view in Fig. 2) which is displaceable laterally 
in the fork d and coated with felt H on one side. On 
the same axis as disc t is the upper end u of the indicator 
z which is widened here and toothed. The lower end of z 
carries a millimeter or circular graduated vernier while the 
primary scale v for this is on the fork d. 

A side weight consisting of little tubes of mercury w is 
attached under fork d, the purpose of which is to turn the 
fork and indicator z at every inclined position of the 
borehole. 

Above the apparatus a clockwork is placed which fixes 
a magnetic needle k' on one side and can turn toothed wheel 
z' with spindle k on the other side. This turning screws 
up rod h turning spring g so far that it brings the bore m 
over the lug n above the spring pressed plate p. The attach- 
ment n can now enter bore m of disc /, raising plate q and 
fixing it between / and p. This fixes the fork on the one 



COMPASS AND PLUMB-BOB METHODS 



133 




FlG.I 








a 



UT'M'^ 



-I Sii 



^ 



stzf 



ra 



7^ 



^h 



JL 



^T 




V - Vo JJ 



Plate VII. — MoUmann's deviation apparatus. 



Fig. 3 



134 DEEP BOREHOLE SURVEYS AND PROBLEMS 

hand, and on the other hand, by the simultaneous raising 
of the bar r attached to q, the nose y of lever hi is liberated. 
This is drawn away by the pressure of a spring action on 
the head of lever s' and the felt-faced disc t is thus pressed 
against the widened part u of the indicator z. In this way 
it is brought to rest and permits of a direct reading when 
the whole is brought to the surface. 

Though the device of MoUmann constitutes a progressive 
step in the science of borehole surveying it is intermittent 
in action. Owing to the pendulum being only allowed to 
swing in the plane normal to the fork beams it rapidly 
comes to rest, hardly 8 to 10 sec. being needed. It is also 
very easily read by the ordinary boring personnel. The 
accuracy of the scale readings is read in 20-min. arcs for 
10 deg. being thus far superior to previous devices; but even 
this accuracy is unnecessarily high owing to its being 
greater than that of the compass. This apparatus is 
accurate, rapid, reliable and sure in action but unfortunately 
it is unreliable in respect to orientation of the deviation. 

Bawden's Apparatus. — This device, invented in Kalgoor- 
lie. West Australia, in 1905 by Wm. R. Bawden, contains 
many features which are to be seen in Gallacher's apparatus 
of 13 years later. 

The inner tube A (Fig. 81) has head joint covers k and ki 
with counterweight sectors g, gi on the loaded axial pivots 
which support the tube A. Tube A is attached by further 
attachments to the counterbalance sectors g, g\. The mag- 
netic needle n is likewise enclosed by a loaded spherical 
housing d and by means of Cardan suspensions all round 
is thus so mobile that its pin always stands vertical. The 
spherical housing d has an opening for filling with fluid 
gelatine and is closed from above by a screw cover and 
hardwood plate. 

For obtaining the dip of the hole two pendulums pi and 
P2 are provided and are rotatable with graduated arcs e and 
/ on metal plates. On both sides of the plates are reading 
glasses. The tube A is connected to the plate by a bow. 
Before using the apparatus the pendulum housing and 



COMPASS AND PLUMB-BOB METHODS 



135 



compass housing are completely filled with warmed gela- 
tine and then adjusted into tube A which is filled with hot 
water to keep the gelatine fluid. Before reading, the latter 
is again taken out. The protection tube A' is screwed over 
tube A and the apparatus sent into the hole. The counter- 
balance sectors always permit a rotation of the internal 




Figs. 81 and 82. — Bawden's apparatus. 

tube in such a manner that the pendulum can always play 
free. On the gelatine solidifying the pendulum and the 
needle are fixed in their positions of rest and these are read 
aboveground. 

The apparatus of Bawden utilizes the principle of Mac- 
George's device as also does that of Cross, ^ which latter 
therefore need not be mentioned here. The Bawden 

1 Denny, C, "Diamond Drilling," pp. 76 et seq., Crosby Lockwood. 



136 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



apparatus does not escape all the defects of MacGeorge's 
apparatus but it is more convenient to handle and more 
robust. Its great disadvantage is that its action is not 
continuous up and down the hole, it having to be extracted 
for every reading. 

Hillmer's Apparatus.^ — Hillmer also adopted the prin- 
ciple of a plumb-bob point let down on to a prepared base, 
as shown in Fig. 83. The cylindrical housing a (Fig. 83) is 
filled with a fluid and is let down on hollow 
rods into the borehole. It consists of a fluid- 
filled cylinder a with a pendulum P sup- 
ported on ball bearings in such a way that it 
will also maintain its upright position when the 
housing is inclined. Above the point S of 
the pendulum is a soft plate G which can- 
not turn and bears a spring F in such a way 
that it keeps off the pendulum point. On 
the upper surface of the plate, freely swing- 
ing on a point, is a magnetic needle N which 
has an attachment A pointing downward. 
A piston K is provided over the needle in the 
housing the rod of which is carried through a 
central opening in the housing top and carries 
on its top end a piston Ki. There is a spring 
Fi between the latter and the top of the hous- 
ing which by its pressure keeps piston K 
in the highest position. In using the device proceed as 
follows : After having lowered the apparatus to the spot to 
be measured, and both pendulum and needle have come 
to rest, a means of pressure (water, compressed air, or the 
like) is conducted through the hollow rods on to piston Ki. 
This presses down K and plate G. The attachment A 
on the magnetic needle and the point S of the pendulum 
now bore into the soft plate and both are thus fixed. After 
raising the apparatus to bank, the position of the two marks 
can be used to get the inclination of the borehole. 

1 Freise, F., " Stratameters and Borehole Dip Measurers," p. 53, Aix-Ia- 
Chapelle, 1906. 



^T 



Fig. 



COMPASS AND PLUMB-BOB METHODS 137 

The device is certainly simple and ready for use at any 
time without delay or special preparation, and it is suited 
to manipulation by the ordinary boring personnel. Of its 
drawbacks we may mention: 

1. The pressing down of the plate; the needle and pendu- 
lum point might be injured by this but it might be regulated 
by controlling the piston pressure. 

2. The waste of time brought about by letting hollow 
rods into the hole. 

3. It has no special centering device and it must be 
exactly centered. At great depths unbalanced rod loads 
upset instruments not specially centered. 

Dr. Freise of Aachen speaks of the apparatus being 
shrouded in trade secrecy, a feature that unfortunately does 
not apply to this apparatus alone. 

Gallacher's Apparatus. — This apparatus was invented in 
Johannesburg in 1918 and possesses features of remarkable 
ingenuity and mechanical skill. It is designed to survey 
both the deviation from the vertical and from the azimuth, 
these to be read direct from the instrument on withdrawal, 
without surface calculations. We enter into some detail 
respecting it here because it appears to have lacked the 
necessary publicity such a device merits. 

It consists of an outer casing a (Fig. 3, Plate VIII) with 
an inner casing b longitudinally pivoted in it by means of an 
adjustable footstep bearing in the bottom end c. 

The inner casing (Figs. 1 to 2a, Plate VIII) carries the 
controlling and recording elements in the form of clock- 
work, plumb bob (in the shape of a weighted cylinder) and 
compass, and spring device for controlling the clockwork 
and fixing the plumb bob and compass at any desired spot. 
This inner casing is suitably cut away and windowed oppo- 
site its weighted side. 

Figure 1 shows the inner casing at the clockwork d end; 
Fig. la shows the other end of the inner casing carrying the 
cylindrical plumb bob e, compass / and the clamping device 
g for both. 



138 DEEP BOREHOLE SURVEYS AND PROBLEMS 

Figure 2 is a view of Fig. 1 turned on its long axis 90 deg. 
with cover on. 

Figure 2a is a view of Fig. la turned on its long axis 90 
deg. partly in section and partly in elevation with cover on. 

Figure 4 is an enlarged view of the plumb bob controlling 
and clamping device g in the inner casing and the compass 
set free with it, Fig. 5 being a sectional view of Fig. 4 on 
line XX. It is possible to have three operative positions 
of the fixing and clamping arrangements for the plumb bob 
and compass, i.e., 

a. Compass needle fixed from independent movement 
with its compass case and plumb bob free to move about 
their pivots. 

b. Compass needle and plumb bob both free with com- 
pass case held against movement on its pivot. 

c. Compass needle and plumb bob both fixed with com- 
pass case free to move on its pivot. 

Figure 6 shows Fig. 4 when condition c above is obeyed. 
Figure 7 shows an enlarged view of the inner casing with 
compass / and that part of the clamping device which 
directly operates it. Figure 8 shows a cross section of the 
inner casing with compass and compass-clamping device. 

In the assembled view (Fig. 3) the upper pivot h and 
bearing are of non-magnetic material, like phosphor bronze, 
as also are the nearest rod connections. In small holes the 
apparatus is placed on the end of the drill rods; in large 
ones it is let down by a flexible wire. Both inner case b 
and outer case a are cast in brass or other non-magnetic 
metal. The inner case is suitably weighted to cause it to 
turn on the end pivots, bringing the registration device 
under the inspection cover windows. The weighting means 
are the lower and heavier portions of the controlling and 
recording elements and the base plates, their centers of 
gravity lying below the center line of the end pivots and 
opposite the inspection covers. The clockwork control 
i (Fig. 1), near the pivot end, consists of a lever escape- 
ment, a train of wheels j, and their cooperating pinions k 
and main spring barrel I. The clock itself d is provided with 



COMPASS AND PLUMB-BOB METHODS 



139 




^^^""^ 


^ 




! '.o; @ 


°l ' 


[k^ 


w 


: ^f^^m 


1 7 \ 

1 lU 


\ •' 


fll 


f : 


' _ Jr- 


til 


|fe| i; 


^^MS 


'^M''- 


||r^^^ 


^ 





140 DEEP BOREHOLE SURVEYS AND PROBLEMS 

independent setting and adjusting mechanism shown at 
m (Fig. 2) ; its dial n can be graduated to represent any 
number of hours, preferably a number not much exceeding 
the maximum time of its employment. The clock is, as 
said, controlled automatically and capable of wide and 
varied adjustment. 

The plumb bob e (Figs, la, 2a) is a loaded pivoted cylinder 
with peripheral graduations for about 110 deg. and it 
oscillates in consonance with any variations in the inclina- 
tion of the inner and outer casings a and b. Its graduations 
can be read through a casing cover glass o (Fig. 2a), which 
carries a zero mark. The spring-operated means for 
clamping this plumb bob are the clamping levers p,p, which, 
when in action, bear on the plumb bob, retaining it in the 
position it assumes at the point to be surveyed. This 
clamping of the bob takes place through the cam plate q 
(Figs, la, 2a, 4, 6). This clamping device permits of adjust- 
ment of the plumb bob and compass at any of the three 
positions a to c above. 

Between the plumb bob e and the bottom pivot in the 
inner casing b is the other recording element, the compass 
/ (Figs, la, 2a, 8). Its box is pivoted at right angles to the 
casing end pivots. Its clamping device is the bell-crank 
lever s engaging cam plate q. This lever projects to hold a 
spring t actuating the releasing and retaining lever u 
keeping lever s engaged in cam plate q and thus, by further 
leverage, engaging the compass box e about and below. 
The compass box is suitably borne and loose bushed for 
leverage clamping by means of springs working in grooves 
from the levers, as seen in Figs. 7 and 8. Cam plate q is 
fixed in its position by a pin v before insertion into the 
borehole and on its removal allows the necessary initial 
engagements to be made. In the position shown in Figs, 
la, 2a, and 4, cam q and its cooperating parts are set by pin 
V. The clock is now set so that after a predetermined time 
the end of releasing lever u will be engaged. This releases 
lever u, the plumb bob and compass being both free (Fig. 8) 
with the compass needle clamped by a spring x. In this 



COMPASS AND PLUMB-BOB METHODS 141 

position the whole of the recording elements (plumb bob 
and compass) remain until the point to be surveyed in the 
hole is reached. In due course a pin y engages with the 
end of lever u (Fig. 1) until finally cam q engages pin z in 
the position shown in Fig. 4. This is the position of the 
clamping device after the apparatus has arrived at the 
survey point in the hole and sufficient time has elapsed for 
the compass box to come to rest. Here the compass box is 
clamped with needle and plumb bob free on their pivots. 
Further movement of lever u disengages a projection or 
tooth giving the position shown in Fig. 6. The ensuing 
movement of cam q actuates levers clamping the plumb bob 
e and, simultaneously by levers and connecting rods, releas- 
ing the compass box and clamping the needle by spring x 
as already said. It is clamped in the magnetic north so 
that the free compass box gives us the direction of deviation 
of the borehole directly; and the graduations on the plumb 
bob relative to the zero indicator on the cover plate give the 
amount of dip, also directly. 

It will thus be seen that this instrument enables the data 
to be clamped or released after insertion and also gives 
control over the recording elements. The clock can be set 
at will independent of its mainspring and both compass 
and plumb bob can also be reset at will. All readings are 
direct with no additional surface computations and each 
element is fully controlled. 

Objections which can be raised against this apparatus are 

a. The mechanism is too complicated and refined for 
small holes. 

h. Readings are not continuous down the hole, each 
point requiring extraction and reading at surface. 

c. Liability to mechanical complications. 

d. Compass unreliable in magnetic strata and lined holes. 

The Briggs Clinophone. — This is a plumb bob or pendu- 
lum device with aural electrical registration applying the 
Wheatstone bridge principle and is employed in precision 
surveys of boreholes. That is to say, it is used where 
deviations of more than 1 in 150 are not permissible, as in 



142 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



some deep freezing shafts. Here contracts frequently 
stipulate a survey capable of registering a deviation of 1 
in 200 or 1 off the vertical in every 200 deep. The normal 
range of this device is about 2 deg. from the vertical. 

It makes and maintains claims to simplicity, cheapness, 
lightness, rapidity and ability to survey narrow deep holes, 
giving a continuous record of amount and direction of dip. 
It was successfully employed at Seaham Colliery Sinkings. 
We are indebted to Professor Briggs for the following details 
and personal notes. 

The Transmitter and Receiver. — The transmitter is hung 
in the hole on the rods and the receiver is situated near the 
mouth of the hole, the two electrically connected with a 
flexible five-strand cable. 




Fig. 84. — Clinophone receiver. 

The transmitter^ has a plumb B (Plate IX) hung on a 
"G" violin string A connected to needle H through the 
wire wrapping of the string. The needle dips into a solu- 
tion (NaS04) F in the vulcanite cup E which has four 
platinum foil electrodes eNes, es and ew, 90 deg. apart (Fig. 
8, Plate IX) each reaching to the cup base. These connect 
respectively to the rods Dn,De,Ds and Dw insulated from 

1 See also Brydon, A. D., Trans. Inst. Min. Engr., Vol. 71, p. 431; Briggs, 
H., Proc. Roy. Soc, Vol. 46, p. 223, Edinburgh, 1926. 



COMPASS AND PLUMB-BOB METHODS 

c. 



Leaiher Washer 
Sweaied Jolnfs 



143 



Fis.2 



^Fis.lO 




Fio. 8 



Vertical Section on b-b 

FI6.1 

Plate IX. — Briggs' clinophone transmitter. 



144 DEEP BOREHOLE SURVEYS AND PROBLEMS 

the outer case and having terminals tN,tE,ts and tw (Figs. 1, 
2). A fifth terminal t is connected to line A and therefore 
H. The strands c are led to the five terminals. The 
cable C goes out to the surface outside the rods. Cup E 
can be inserted in only one position and is replaced by a 
wooden clamping plug when not in use. A tail piece is 
hung 30 ft. below the transmitter to aid centering. Figure 
84 shows the receiver connections which are in a wooden 
box 11 by 10 by 7 in. The cell h is an ordinary pocket torch, 
4-volt refill, hence the claim to cheapness, and Z is a small 
induction coil, its secondary connected to condenser C2 for 
clearing the telephone note. The five strands of the cable 
are attached to terminals Tn,Te,Ts,Tw and T (the last is 
the plummet strand, the others the above mentioned t,y, 
tE,ts and tw of Figs. 1 and 2, Plate IX) and from there to the 
respective electrodes of the transmitter cup. Needle a 
is held by the operator and loose flexed to the dish Ei 
which holds salt solution (say, NaS04) and has four plati- 
num electrodes e'^, e's, e's, e'w. It has a glass floor with a 
dial scale the concentric circles of which are minutes of arc 
and the radial lines 5-deg. bearing each. The operator 
wears a low-resistance headphone R, one receiver of which 
is coupled to the terminals 1 and 2, giving NS deflections, 
the other to 3 and 4, giving EW deflections. The rods have 
a special orientating coupling by external scribing in relation 
to the vulcanite cup E.^ 

It will be seen from the wiring diagram (Fig. 85) that the 
wiring system involves two applications of the Wheatstone 
bridge connections to the liquid resistances of the earphone 
indicators. Needle a is moved about the receiving dish 
base until the noise in both earphones is a minimum, when 
a occupies the same position in the dish as plummet needle 
H (Plate IX) in the transmitting cup, and this is read on 
the cup base dial. The receiver connections are reversed, 
as in Fig. 85, because H will occupy a position diametrically 
opposite to the hole dip. The bob must be at rest in the 
hole to get a clear minimum sound and it takes about 10 

1 Brydon, a. D., op. cit., p. 437. 



COMPASS AND PLUMB-BOB METHODS 



145 



min. to come to rest. The needle position is illustrated in 
Fig. 86 and is seen to be at the intersection of two equipo- 
tential lines the dotted circle being the actual range of the 
plummet needle which is thus the reading needle range. 
Differing connections, of course, vary the mesh of equi- 
potentials, and a connection suited to a person with uneven 





Fig. 86. — Equipotential lines in receiv- 
ing-dish. First arrangement. 




Fig. 85. — Clinophone wiring diagram. 



Fig. 87. — Equipotential lines in receiv- 
ing-dish. Third arrangement. 



hearing is found by short-circuiting the electrodes in adja- 
cent pairs and coupling an earphone between the pair using 
the good ear only. Such an arrangement (Fig. 87) will 
give a locus of minimum noise points as a straight line. 
Short-circuiting on another cardinal point electrode we get 
another minimum noise line. The intersection of these two 
loci can be easily and exactly fixed and is the point sought; 
now read off its dip and bearing in the dish scale. The 
average reading error of an observation is about 5 min. of 
arc with an 18i^-in. plumb bob, and this may be reduced by 
carrying a longer plumb line or by having a check reader 
and alternative connections. 



146 DEEP BOREHOLE SURVEYS AND PROBLEMS 

The instrument we have had the advantage of examining 
was suited to a 4-in. borehole and was about 35 lb. in weight, 
40 in. long and had %6-in. walls. It is efficient and 
certainly cheap and convenient and has been tested for an 
external pressure of 600 lb. per square inch. 

Kegel's Apparatus. — This is an ingenious floating 
plunger plumb-bob device invented by the mining engineer 
Karl Kegel of Freiberg in Saxony in 1919^ and capable 
of many alternate constructional rearrangements and 
modifications. 

It gives the apparatus at the place being surveyed a 
definite direction from which it cannot deviate. In Fig. 
1 (Plate X) the heavy rod h or chisel c or both are attached 
to the main rods a as also are guide devices d and plumbing 
medium e. The action of the last named will be seen 
from sections EF and CD, it being premised that other 
constructions of plumb and connecting tubes will attain 
the same end. The plumb g here floats in the plumbing 
fluid h and has a bottom plunger carried through the guide 
i SO that as a result of the buoyancy it always floats upright 
over the guide hole. The upper plunger of plumb g pro- 
jects through three contacts j, k and I and lies against a 
particular contact should there be any borehole dip. The 
guide casing recess belonging to the particular contact 
concerned has its own electric motor and current supply. 

There are thus three of these, one for each of j, k and I. 
The motion of any one motor is transmitted by a worm and 
worm wheel m on spindle n. The wheel and spindle are 
connected by spring and groove in such a way that the 
spindle may move axially through the wheel. The spindle 
passes through the fixed nut o on the housing or casing d 
and is displaced according to how it is rotated. With 
similar rotation any two given motors will turn back 
accordingly and so displace their spindles backwards. 
Thus the spindles act as centering screws. On being let 
into the hole the three motors with special supply current 
may be so switched in as to draw in their spindles and 

1 German Patent No. 317,663. 



COMPASS AND PLUMB-BOB METHODS 



147 



reverse again when the survey spot in the hole has been 
reached, thus pressing them out against the borehole walls. 
The worm wheels thus move back on the spindles and press 
back the contact springs p interrupting the direct-current 
supply so that only the current to the plumb g and contacts 
j, k and I remains. The motors can be set in action at any 



I 



Idl : 



:■ g 

^4 




Sec+ion G-H 




^ Section E-F 



Section C'D 



FlG.1 

Plate X. — Kegel's apparatus. 

time by means of another current supply from outside; 
thus the centering may be actuated at will. Instead of 
the plumb g and its connections, a gyroscope or direction 
indicator (magnetic needle) may be employed which will 
maintain a definite horizontal direction by the action 
of an electric motor or plummet, giving thus not only the 
amount of dip but its direction also. For example, 
the plumb g can be held to a definite orientation by a 
gyroscope and the upper plunger rod of the plumb can 
give a definite dip. By varying the dip and bearing of 
this plunger the direction of the attached boring tool can 



148 DEEP BOREHOLE SURVEYS AND PROBLEMS 

be altered to give any desired curvature of borehole. We 
may get the centering motion without the worm wheel 
gearing in other ways, e.g., by wedges displaced forward or 
backward. Likewise in place of the electric motor other 
power can be employed, such as valves operated by the 
plumb or a gyroscope. The direction apparatus can be 
fixed solid or detachable on the rods. 

The greatest demerits of the device are that it is inter- 
mittent in action and there is no device to prevent turning 
on insertion or extraction. 

Maillard's Apparatus. — This simple and cheap device^ 
consists chiefly of a simple plumb-bob electrical contact 
apparatus. Figures 88 and 89 show a longitudinal section 
of the apparatus which is a series of hermetically sealed 
hollow rods a connected to a body b, which has a play 
of about 4 mm. in the hole lining A. The body h has 
external guide springs c for centering. In the upper 
part of 6 is a circular ebony membrane d with an opening 
/. Below the membrane cZ is a conical recess. A cable g 
passes through/ and holds a brass plumb bob h of cylindrical 
shape with a spherical end. This latter rounded part of 
the bob is the only part allowed to make contact with the 
slanting sides of the recess; it is rounded to lessen friction 
on being moved up or down. Cable g is an insulated 
electric wire passing through the hollow rods a. 

It will be seen from Fig. 89 that the complete electric 
circuit is by way of the source j at the surface, through the 
cable g, the plumb h, the borehole casing A, the galva- 
nometer k and back to the source j. 

When taking a measurement the apparatus is let down 
into the hole, which is already provided with casing A, 
by means of the hollow rods a, successively screwed up 
at the surface in the normal way, to the desired spot to be 
surveyed. The partial turns of the tube a which may be 
called ai, a2 . . . an are related to a fixed starting direction 

1 Pechelbronn Societe anonyme d'exploitations minieres et Georges 
Maillard. French Patent July 27, 1925. German Patent No. 492,573, 
Mar. 4, 1930. 



COMPASS AND PLUMB-BOB METHODS 



149 



such as the true north. The angular displacements of the 
apparatus in the hole are found thus: When plumb h is in 
last contact {i.e., the last touching position before disen- 
gagement) with the sloping side of 6, we are at the limiting 
position at which the circuit is closed and the galvanometer 



i}^ 




Fig. 



Fig. 89. 



deflects. By slowly hauling up the plumb bob we can find 
this spot, for, after it, the contact is interrupted and the 
needle of the galvanometer adjusts itself back to zero. 
We thus know the length of the plumb line hanging in h 
from /, because we know the amount hauled out to make 
last contact. Thus it will be seen that any angular posi- 
tions ax, 0:2 ... «„ given by the apparatus correspond to 
certain critical lengths U, h . . . l„ of the cable g. These 



150 DEEP BOREHOLE SURVEYS AND PROBLEMS 




Timing 
'Waich 



can be plotted for maximum, «m, Im and minimum a, 
L values of angular devia- 
tions and lengths. 

In Fig. 90 we have an 
easy way of getting the 
borehole inclination i at the 
depth concerned. Con- 
struct the triangle xyz in 
which the angle xyz and 
the side xy are known from 
construction and the side xz 
is also known, being equal to 
the maximum length hi 
above (previously obtained 
by raising and lowering h 
and plotting; to this add the 
length of the plumb bob). 
The angle sought is zxy = 90 
deg. — i. Repeat this pro- 
cedure from place to place to 
get the amount and direction 
of dip, the latter being more 
satisfactorily obtained by 
taking three such readings at 
120 deg. apart in azimuth at 




-BaHery 
Case 

Shell 



':jk-V.Ba fiery 
^^ '^(10 Used) 



Flexible 
Bctffery Wire 



,, Refracting 
Spring 

Universal 
/Bearing 

Elecfromagnef 



.-Plurnb Bob 

Plunger 
^yConfrolled 
hy Magne-f 

^ Pa per Disk 
'-Cork Disk 



I ^-Tapered 
Sfeel Nose 



YiG. 90. Fig. 91. — The driftmeter. 

each given spot and making a graphic or tabular check. 



COMPASS AND PLUMB-BOB METHODS 151 

It would be difficult to imagine a simpler device and it has 
recently been protected in Germany. We may visualize 
the following possible defects: 

1. The angular positions ai, a2, etc., being dependent on 
the inner rods are not free from objections. 

2. Friction of the cable at the membrane and hindrance 
to the same should pressure water and mud penetrate the 
many joints. 

3. The device may become cumbersome in deep holes. 

4. The borehole must be lined all the way. 

The Driftmeter. — This is a recently developed American 
apparatus^ being a pricking plumb-bob device. The instru- 
ment (Fig. 91) is about 3>^ ft. long and weighs about 30 
lb. and is suited for rope lowering with a depth-measuring 
appliance or it may be fitted to the rods. The principal 
parts are the clock, the ten 13-^-volt batteries, the leaden 
plumb bob fixed on a solenoid or electromagnet and the 
magnet-controlled pricker plunger passing 
through a universal bearing which has a 
mobile suspension. Under the pricker is 
a 2%-in. registering paper (Fig. 92) divided 
into 15 circles of 1 deg. each and is thus 
suitable for filing. Space is provided on the 
back of this paper disc to record depth, well ^^^- 92.— Drift- 

mctGr rGcord 

number and other data. In this way deflec- 
tion angles are found direct to about 15 min., no preliminary 
work being necessary, the instrument being ready for use 
as soon as a new paper disc is fitted and the clockwork set. 
The clock can be adjusted to a definite time; then by the 
contact brush making connection with the battery and 
magnet the plunger is set into action perforating the paper 
disc. A retracting spring keeps the plunger off the paper 
when the current is shut off. The resulting reading is 
direct and needs no computation. The same sheet can be 
repeatedly used by marking each perforation as made, so 
getting a series of indications of the deviation. Since it 
requires no special skill the ordinary boring personnel can 

1 The Driftmeter Co., Inc., Tulsa, Oklahoma. 




152 DEEP BOREHOLE SURVEYS AND PROBLEMS 

use it, thus giving a constant cheap control on the progress. 
The plunger being made of a non-magnetic alloy or lead 
eliminates any chance disturbing magnetic influences. It 
can be made in sizes as low as 1.9 in. for running inside 4- 
in. drill pipe. Its greatest disadvantage is that it is inter- 
mittent in its action, having to be hauled out after each 
record, the clock being reset and, if necessary, the paper 
disc changed. 



CHAPTER VII 
PENDULUM METHODS 

Introductory Note. — The physical features of the pendu- 
lum which are essentially those of the plummet have been 
among the great attractions of physicists for the last 300 
years. The outstanding features marking the discoveries 
of Newton, Foucault and Kater are all incorporated in 
modern borehole survey instruments of this class. 

Our reason for distinguishing this suite of apparatuses 
from the compass and plumb bob section is that generally 
the plumb bob is used as a dropping pricker, a plunger 
pricker, a balanced vertical bar, or in some other way not 
fully utilizing its oscillatory properties. This is not a rigid 
statement, since many compass devices also apply the 
swinging bob. 

The pendulum proper is being understood when we con- 
sider the elliptic or circular paths of a hanging bob or rigid- 
limbed pendulum. It has the outstanding advantage of 
independence of the magnetic north or the constitution of 
its surroundings, working and obeying its astronomical 
north-seeking faculty as well in magnetically disturbed 
regions as without them. Its possibilities are evidenced by 
the success of submarine and aerial navigation, since 
gyrocompass action is an adaptation of the pendulum 
principle. 

Koemer's Apparatus for Measuring Deviation. — This 
device, which is essentially a spring pendulum apparatus, 
was invented in 1906 by G. Koerner, an engineer of Nord- 
hausen, Prussia, the suspension of the plumb line or pendu- 
lum being altered by mechanical means and the oblique 
positions of the same recorded photographically. 

In Fig. 93 the tube a is kept to the hole center by the 
feeler spring wheels 6 pressing on the sides of the borehole. 

153 



154 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



The central plate c holds a frame d carrying a graduated 
glass plate e. A rotatable spindle / in the center of these 

& 




Fig. 93. 



plates c and e carries a plumb line g on an arm h, and also 
a graduated index i slotted to take the plumb line. In 
the bottom of the tube are four electric incandescent 



PENDULUM METHODS 155 

lamps i for illuminating the glass plate e, the index i and the 
plumb line g. There is also here a camera A; and a rolling 
film n driven by clockwork I and electrically controlled 
by the cable fine m. The frame d and glass plate e and 
the plumb line g can be placed at an angle in the tube a 
by means of the spring o on rod p and spring q bearing on 
plate c. 

The staple r is arranged to carry a lowering rope. If the 
apparatus is suspended by rod p the frame and springs will 
occupy the positions shown bold in Fig. 93, the springs 
being compressed and the rod / being parallel to the walls. 
If, however, the apparatus is suspended from the staple r 
the springs are released to the dotted position of Fig. 93, 
forcing the frame to the inclined position. 

To make a reading the appliance is suspended by rod p 
with two external points on its casing in the meridian. 
Then plumb fine g takes the position of the dip, and so the 
position of the dip of the borehole orifice is found. This 
position is photographed from below. Suspend the appli- 
ance on the staple r without turning and bring the plumb 
line spindle / into the inclined position. The plumb line 
g now assumes a position which is determined by the dip 
of the borehole and the inclined position of 
the axis /in accordance with the parallelo- 
gram of displacements. The film n is 
advanced by electrically releasing the 
clockwork I ; the lamps j are again switched 
in and the new position of the plumb line 
recorded photographically. By compar- 
ing the two readings a diagram of the type 
shown in Fig. 94 is obtained, from which the deviation 
is found. The extent of the dip is calculated from the 
amount of deflection of the plumb line from the center of 
the scale on e and i and from the length of the plumb line 
itself. The distance of the bottom of the plumb line is 
read on a special scale on i. 

The objections to the apparatus are as follows: 

1. Double suspension is liable to introduce turning errors. 




156 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



2. There is no guarantee of continued alignment of the 
meridian indexes. 

3. The feeler centering springs are liable to error and they 
also preclude the adoption of this method 
in very narrow boreholes. 

4. Springs are objectionable in boreholes 
holding water under high pressure. 

5. The apparatus becomes too involved 
if attempts are made to obtain continuous 
readings. 

Erlinghagen's Apparatus. — This appa- 
ratus introduced a significant change in 
the construction of deviation instruments. 
It is a pendulum apparatus with electrically 
operated registration mechanism. It con- 
sists essentially of an electromagnet 
operated pendulum and a clockwork-driven 
recording paper strip in which the pendulum 
pointpricks a set of definitely arranged 
marks. The clockwork is also released 
simultaneously with the pendulum by 
means of drawbars. 

Provided the apparatus keeps from turn- 
ing on being let down the hole, it is a very 
suitable apparatus and Chief Engineer 
Erlinghagen of Nordhausen, the inventor, 
tried various devices to attain this end. 
He first employed a longitudinal slit g down 
the apparatus c (Fig. 95) with the rope a 
held in the slit. This was not entirely 
satisfactory. Later he employed telescopic 
lenses held by counterspring nuts in the apparatus, as in 
Figs. 96 and 97, which solved the difficulty. 

Figure 96, left, shows the entire apparatus assembled 
ready for insertion in the hole with the lenses collapsed. 
Figure 96, right, shows the device in the extended condi- 
tion. Only electric current is used for the determination 
apparatus. The tubes can be let out by loosening a brake 





Fig. 95.— Erling- 
hagen's original 
centering device. 



PENDULUM METHODS 



157 




Section A-B Section C-D 



Figs. 96 and 97. — Erlinghagen's new apparatus. 



158 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



f which actuates two drums on which a thin wire rope h 
to the head of the lower tube is wound. For closing the 
lenses up again spiral springs on the drums coil up the wire 
automatically. On the top end of each tube is a headpiece 





Side View Section C-D 




C — 




Section E'F 
Fig. 98. — Centering device. 



Section A-B 
-Erlinghagen's electromagnef. 



X in which the measuring apparatus (Fig. 97) is guided by 
the thin ropes h exactly on the center line of the tubes or 
lenses. The lower spiral spring i and the levers k serve to 
hold the lowest lens of the telescope exactly in the middle 
of the borehole when in the extended condition. It will 
be seen that in small diameter boreholes the brake loosening 
device and telescope lenses would be inadvisable owing to 



PENDULUM METHODS 159 

the thickness of the lenses themselves (which is at least 
60 mm. inside width for high water pressures and 130 mm. 
outside). Therefore a new form of fixing device for 
simultaneous centering was adopted by Erlinghagen in 1906 
in cooperation with Professor Klingenberg of the General 
Electric Company in Berlin, as shown in Figs. 98 and 100. 

The borehole magnet was made by having an I-shaped 
bronze frame, between the webs of which on each end a n- 
shaped iron was placed enveloped by a magnetic coil. 
The legs of the iron were beveled (Fig. 99) corresponding to 
the internal diameter of the borehole. The coils have to be 
absolutely watertight. The coil was wound with enameled 
wire and the bearing spots repeatedly insulated from one 
another and the whole placed in a zinc case and waxed up. 
The neck has a soldered bridge through which the winding 
wire is carried well insulated. The construction has been 
tested for hours under a pressure of 9 atm. 

Figure 98 shows the centering device where we have three 
link-arm borne steel rolls pressed outward together by a 
strong central steel spring, from which it swings down to 
the bottom of the apparatus in fixed links. Above, it is 
movable up and down by a hnked ring and a movable 
center bolt. There are three of these centering devices, 
one to center the upper magnet, another the lower magnet 
and the other to hold the measuring apparatus properly in 
the middle. The measuring apparatus (Fig. 100) has a 
powerful frame of three steel rings connected by two longi- 
tudinal ribs having, in the upper part, a glass encased clock- 
work. Under this a roll paper 50 mm. wide winds from roll 
Ti over the cork-lined plate j) on to roll r2 with uniform veloc- 
ity, only roll r2 being clockwork driven. As the angular 
velocity of the clock is always the same, that of the paper 
increases the more paper is wound on to r-i giving a uni- 
formly accelerating motion. To control the time points 
of the measurements the paper must move uniformly and 
this is done by means of the string drive s on roll r^ which 
has a slipping arrangement. Under the paper strip moves 
the point of the universally suspended spring pendulum. 



160 DEEP BOREHOLE SURVEYS AND PROBLEMS 

C-D A-B 




Fig. 100. — Erlinghagen's measuring apparatus. 



PENDULUM METHODS 161 

The pendulum, being very sensitive to shocks and taking 
about 20 min. to subside, has a hair brush damping device 
h which brings it to its position of rest in about 45 sec. 

For working the measuring apparatus a horseshoe magnet 
m on the floor of the apparatus is switched in so that con- 
nection is made by way of the bearing plate e which is 
attracted downward. Plate e is connected by drawbars to 
the clockwork. The weight of the clockwork is taken by 
springs / so that the magnet has very little force to over- 
come. The point of the pendulum sticks up into the paper 
strip when measuring, and at the same time four points t, 
arranged in the center ring and which lie on concentric 
circles on the periphery of the guard tube, mark four points 
on the paper strip, by which we are able to recognize the 
center point of the measuring figure at that instant. 

The conductor wire for the magnet coils goes along one 
of the long drawbars to a clamp for current rod u. The 
head here is specially sealed against entry of water under 
high pressure, thus preserving the clockwork and magnet. 
This is done by means of opposed nuts c and copper 
rods k on floor h bushed to the insulating plate I and slip 
rings d,d. 

The direction line of the paper may be noted on the out- 
side of the tube with the whole apparatus above it, so that 
on letting it into the hole one knows how it stands. The 
conductor and lowering rope are all in one, the conductor 
being insulated with cement, bitumen and tape. 

The inventor gives details^ of surveys carried out with 
the apparatus, which did not turn on extraction or insertion, 
and these facts were checked by an investigation in a blind 
shaft between two levels belonging to the German Solvey 
Works in Bernburg. The results of two surveys at Solvey- 
hall with the apparatus and a later normal instrumental 
survey check are to be seen in Fig. 101. A series of 160- 
mm. tubes were arranged for the apparatus test; the normal 
survey shows a constant survey traverse distance from the 
apparatus survey. Erlinghagen's apparatus marked a new 

1 Gluckauf, p. 743, June 15, 1907. 



162 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



epoch in the evolution of borehole deflection apparatus; 
it was the impetus to many later designs and constructions. 
It conquered the continuous record problem, if however 
crudely, successfully. We may mark from its inception 
the rapid evolution of new methods which began in the 
first decade of this century. Its chief drawbacks are: 

1. It is costly and complicated to make. 

2. It is heavy though easy to manipulate. 

3. Its mechanism and tubes limit the diameters for which 
it can be adopted. 




Firsi- Measuremenfwifh Apparatus 

Second " 

Normal ]nsirumeniail Survey 



Fig. 101. — Checked survey by Erlinghagen's method. 

4. Pin-pricking devices are crude and likely to cause 
confusion in reading. 

5. Moisture is likely to injure the apparatus and cable. 
Thurmann's Apparatus. — This apparatus is built on the 

proportionality principle, the basis of the lead-basket 
plumbing method, but it greatly extends the limits of 
applicabihty of that principle. 

H. Thurmann, Sr., of Halle obtained reliable results 
with his apparatus, which is a double plumb bob and linked- 
tube device, at fair depths. The invention^ (Figs. 1 to 9, 
Plate XI) consists of straight tubes joined by special cruci- 
form joints movable in all side directions but not rotatable. 

1 Organ des Verein der Bohrtechniker, No. 17, p. 190, 1909. 



PENDULUM METHODS 



163 





FlG.2 



Fie. 3 




Fie.4 









F/G.l 






Fi6.6 Fis.7 Fie.8 

Correct P/umb Faul+y but Faulty and 

Markings Usable Workings Useless Markings 



Fie. 3 



Plate XI. — Thurmann's deviation apparatus. 



164 DEEP BOREHOLE SURVEYS AND PROBLEMS 

An apparatus t is arranged in each link tube ri,r2, etc., and 
called a ''pot head," owing to its first being made pot 
shaped. On the floor of this head rests a cork-lined base 
nil (Fig. 5) covered with tin foil and having impressed coor- 
dinate axes. A tong-shaped device s above the head has 
one fixed z and one spring-moved limb s (Fig. 2) which 
carries the plumb weights I. From the latter in each head 
or top there is a pair of common threads or wires; this 
common wire is laid over the transom d carried by the 
tongs. In the base of the little trestle of the tongs is an 
adjusting piece n between set screws o with two fine holes 
for guiding the plummet fibers. This permits of a hair 
adjustment of the plummet points exactly perpendicular 
over the zero of the coordinate axes arranged under the 
head on a perfectly horizontal plate. 

The gudgeons of the cross joints/ of the link tubes lie at 
right angles to one another in their crossing vertical planes. 
The coordinate axes of the marked plate and of the tin-foil 
plate have definitely arranged and assured symmetrical 
positions on the whole of the plumbing heads. Thus in 
each tube of the linked series we have a separate measuring 
operation assured independent of its neighbor. It does not 
matter if the break points between two tubes do not lie on 
the axis of the borehole, because the preceding and succeed- 
ing errors compensate for each other. In horizontal pro- 
jection we then have a simple figure of the deviation of 
each tube. The metal plumb bobs are not affected by 
water, chemicals, pressures or mud, thus combating some 
of the objections to Erlinghagen's and Haussmann's appa- 
ratuses. The fundamental idea of the apparatus will be 
clearly seen by considering two equally swinging pendulums 
side by side, especially when they have a small difference in 
length. In each apparatus are two plumb bobs on a com- 
mon string. The string is led over the transom, and when 
let down in a dipping tube the plummets mark parallel 
lines on the cross axes at a corresponding distance from the 
position of rest. Should the line be at any instant at greater 
or less distance than the normal case provides, an oblique 



PENDULUM METHODS 165 

line will be shown. A graduated sight on the uppermost 
link is used for orientating in the vertical against the coor- 
dinate axes. Thus the plumb line can be viewed at any time 
and a new marking plate can also be put in at any time. 
In this way any doubtful measurements can be recognized 
at once and remedied at any time, an advantage which did 
not hold for the predecessors of this apparatus. In previous 
instruments a series of measurements below each other 
necessitated separate readings and extractions for each, or 
separate depth readings at each place with all the attendant 
trouble and waste of time. Again errors increase with the 
depth. 

This apparatus can be arranged in lengths to suit the hole. 
For a 240-m. hole, say, Thurmann would not employ sixty 
4-m. tubes but ten or at most twenty tubes respectively 
24 or 12 m. long. There is a special plumb for each section 
of hole surveyed so that any errors cannot be cumulative. 
Moreover, each error can be corrected, as said above. 
Therefore it is only necessary to correctly orientate the 
whole apparatus from the surface down, and to aid this 
direction rods (Fig. 9) are used. These are a series of tubes 
equal in length to the link tubes and having tooth and 
notched ends connected by overscrewed thimble joints 
to prevent them rotating. The above noted diopter is 
adjusted to the direction rods on exactly the same line 
as is chosen for the uppermost plumbing section of the link 
tube. In this way the coordinate axes of the marking 
planes lie sectionally in exactly uniform orientation for 
plumbing. 

Freezing shafts are best plumbed from the center by this 
device, the center being the coordinate axes center. 

The inventor claimed that the method was cheaper than 
its predecessors for freezing shafts and also surer; that it 
was unaffected by water, mud, chemicals or pressures and 
that it was direct and easily controlled. Among its 
demerits we may mention: 

1. There is insufficient provision against relative turning 
of the tubes; this spoils the deduced results. 



166 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



2. It is heavy and cumbersome and thus not suited for 
great depths. 

3. It is not easy to manufacture and in some cases, i.e., 
big deviations, will be difficult to manipulate. 

4. It uses up more time than a lighter and simpler 
device. 

5. It has too many movable parts. 

The Denis-Foraky Teleclinograph. — This is a pendulum 
apparatus and one of the best known of the modern 
precision devices employed in freezing shaft boreholes.^ 
It is remarkably accurate, being in many cases somewhat 
of the order 1 in 3,000. ^ The principle is best understood 
as follows: 

Imagine a cylindrical tube (Fig. 102) of length AO with 
a system of rigidly orientated coordinates XF on one end 
when in situ in the hole. Knowing the 
coordinates of o' and the projection of A 
on the coordinate plane, we also get the 
position of the axis zz' of the tube which 
on a centered plumb is the hole axis also. 
Then by making a series of 10-m. interval 
observations we can get the borehole trace 
in 10-m. stretches projected on the horizon- 
tal plane. The freely oscillating pendulum 
A will, if given an initial impulse, describe 
a surface the trace of which on plane XY 
will be an ellipse with center o', which is the 
vertical projection of A. More correctly, 
but differing not sufficiently to affect the results with such 
small angles involved, it is the sphere to which the above 
plane is a tangent upon which the trace is generated. On 
the sphere parallels are traced to the axes XX' and YY' at 
a distance k and actually occupied by the conducting bars 
(reglets) on which the pendulum point contacts every time 
it crosses one, closing a circuit with a registering apparatus. 

^ See a full description in Prospectus of Foraky, Societe anonyme d'entre- 
prise de forage et de foncage, Brussels. 

2 Adam, D., Colliery Engineering, p. 414, Nov. 24, 1924. 




Fig. 102. 



PENDULUM METHODS 



167 



The movement of the point on its elhptical trajectory can be 
represented by that of a point moving uniformly on a circle 
of the same amplitude (sinusoidal law of the pendulum). 
In particular the passages over the bars at a, b, c and d 
will synchronize with the points of the same order a', &', 
c' and d' on the circle (Fig. 103) and o'p measures on this 
figure, y, one of the desired coordinates for finding zz\ 




Y" 9 



Fig. 103. 




This uniform circular synchronous motion is indicated 
aboveground by a registering pen in the receiving appara- 
tus; an electromagnet records the passages over the bars 
by controlling the penholder in the circuit. 

Thus we may get the figure o", a", b", c", d" (Fig. 103a), 

the last four points being the passage points of the pendulum 

over the bars. The value of y deduced from the diagram 

will then be 

o"mk ,.^s 

y = -p^ (11) 

The same reasoning with another projection following 
the other system of bars (reglets) would give from the same 
diagram completed by the other four points of contact:^ 

o"nk , . 

X = -pr (11a) 

The ratio of the recording pen and the transmitting 
pendulum is k" /k. k" and k'" depend on the values of the 
lengths OX and OY, usually different. 

1 FoRAKY, loc. cit., p. 71. 



168 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



The apparatus itself is in three distinct elements; the 
transmitter for the base of the borehole, the surface 
receiver connected electrically to the transmitter, and the 
lowering rods with orientation couplings. 

The transmitter is a strong, pressure-proof, steel tube 
with a pendulum, the trajectory grid plate and the electrical 
connections inside. The pendulum^ (Figs. 104, 104a) 





Fig. 104.— The Denis-Foraky tele- 
clinograph pendulum. 



Fig. 104a. — The Denis- 
Foraky teleclinograph 
pendulum. 



has a Cardan suspension at A the functions of which are 
resolved in an elastic system made up of two crossed springs 
(Fig. 105). The system has the property of acting in 
such a way that the instantaneous centers of rotation of the 
pendulum may be taken as coincident with A. The pendu- 
lum is not allowed to swing freely under the force of gravity. 
No two similar double systems constitute a suspension 
without play or friction, and this method of construction 

1 Haddock, M. H., "Location of Mineral Fields," p. 92, Crosby, 
Lockwood & SonSj London. 



PENDULUM METHODS 



169 




Fig. 105. 



equalizes the elasticity constant proper to each of the two 
perpendicular axes, making it the same in all directions.^ 

An ingenious mechanism gives the necessary impulse 
to the pendulum at each station. For 
convenience in reading, the ellipse caused 
by the pendulum under this impulse 
should be as nearly a circle as possible. 
This mechanism consists of a crank on 
point P (Fig. 106) capable of being dis- 
placed along its vertical axis. It is 
brought to its initial angular position by 
a coiled spring and to its vertical position 
by a plate spring. By the action of a 
surface-operated electric motor placed above the pendulum 
top, a half turn is given to the coil spring and simultane- 
ously, by means of a ramp, the crank is 
displaced on its vertical axis. P strikes 
against a copper dome on the pendulum 
and the crank is liberated from the action 
of the motor, and under the influence of 
the spring it describes an arc aM and rises 
back to its former position. Point a, struck 
by P, describes a tangential trajectory to 
the arc. At the moment of release a is 
going along the tangent M and the pendu- 
lum has to describe the ellipse of major 
axis NN'. If the impulse is suited the 
path NN' will equal a circle MM'. 

Actually in the grating or grid the thin 

bars (reglets) or coordinate lines are fine V 

grooves cut in the spherical silver grating 

plate (Fig. 107). The pendulum point 

(Figs. 104 and 108) breaks circuit with 

the grating surface at these coordinate lines, the break 

being recorded by the electromagnet controlled pen in 

the surface receiver. This receiver (Fig. 109) is a 

^Loc. cit., pp. 72 et seq. The counterforce of the cross springs in the 
suspension is analyzed here with the aid of Fig. 104. 




Fig. 106. 



170 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



rotating plate with a paper sheet on which the pen 
traces a low-pitch spiral each circuit synchronizing with 
the pendulum swing. The pen (Fig. 109) is on the 
jointed system consisting of an isochronous regulator 
ensuring that the periodicity of the pen circuit is constant 
for all positions. The trace of the grating pen is an 
enlarged reproduction of the pendulum swinging contact 
figure owing to the action of the electromagnet on the pen. 
This enables the coordinate axes XX and FF to be drawn. 




The grooves of Fig. 107 form these axes by causing the 
breaks in the circle. The coordinates of the grating center, 
with respect to the vertical, are obtained from the diagram; 
thus 

X = \^X 

and 

x"/k" = x'/k 

Using a coordinate length of 10 m. 

Z/10 = x/l 
and since 

X = x"/k" . lOkC/l (lib) 

we get for a 10-m. length 

X = x"/k" . 10/cC (lie) 



PENDULUM METHODS 



171 



X is scaled direct from the diagram using the center as zero 

10A;C 
and having the indexes at the divisions ± — . — and placing 

it so that these indexes coincide with the lines y'y', y"y" 
(Fig. 110). 1 




Fig. 110. 



-Actual diagram made by teleclinograph showing method of measuring 
deviation by coordinates. 



There is a special orientating coupling which allows the 
rods to follow the hole curvature but maintain their surface 
orientation.^ Figure 111 is a survey by the teleclinograph 
checked from shaft records later. It was taken in the No. 
8 borehole of the Steaua Romana No. 17 suite of shaft holes 
and well illustrates the plan wanderings of a hole. It was 
surveyed in 1925 and is discussed by Friedenreich.^ 

Kinley's Inclinometer. — This instrument, invented by 
M. M. Kinley, the oil-field fire fighter of Tulsa, Oklahoma, 

1 After Adam, D., loc. cit., p. 412. See also Schmidt, F., Trans. Inst. Min. 
Eng., Vol. 52, p. 178. 

Friedenreich, O. L., Analele Minelor din Romania, p. 693, November 
1926. 

* FORAKY, op. cit., p. 82. 

3 Ibid., p. 707. 



172 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



does not render the direction of deviation but the amount 
only. It is well suited to rapid, simple and fairly accurate 
records for working or completed wells. It is essentially 
a pendulum or plumb-bob recording device in a cylindrical 
watertight housing. The lower end of this housing is 
externally threaded and it is attached to the bit or core 
catcher. The original Kinley instrument^ was lost in a 
Texas company well. Here the recording unit (Fig. 112) 
includes a support frame B with an upturned arm on a 





■Ay 






r^2° 


400 ^X 

350//^^ / 
/^ 580/ 


\s30 

5^550 

\io 
Mo 








A/ 


\ '/ 




v 


20 20 


40 60 80 100 

— 1 — 1 1 1 



250 



~y 



Fig. 111. — A Rumanian borehole surveyed by the 
Denis-Foraky teleclinograph in 1925; plan of the hole 
No. 8, "Steaua Romana" 17. 




Fig. 112. 



vertical plate on its upper end. The lower end of this plate 
has an inturned arm for mounting a rewind mechanism. 
Ball bearings A on the inturned arm at the lower end of the 
plate assist the upper ball bearings A to hold the recording 

1 Smiley, T. F., Oil Gas Jour., p. 44, Apr. 25, 1929. 



PENDULUM METHODS 



173 



device. The rewind mechanism is a spool on a 
shaft carrying a blank record strip C. The ends 
of this shaft are fixed in horizontal aligning open- 
ings at one side edge of the plate and bracket. 
The worm gear D fixed on a shaft has one side 
against the plate and its opposite side face in a 
vertical plane with the inner face of the flange of 
the spool. The rewind spool is secured on the 
shaft between the worm gear D and the bracket 
and has side flanges. About midway between 
the rewind spool and the upper inturned arm, 
and at the side edges of the plate, is a pair of 
idler rollers E mounted on pins fixed in the plate 
and extending inward and lying parallel with the 
rewind spool shaft. Over these the record strip 
passes from the spool (Fig. 112) presenting a flat 
surface for the inking device. The part of the 
strip down on the other side winds on to the 
rewind spool. The spool is driven by a spring 
motor F with a worm screw engaging in the worm 
gear in the space between the rewind spool and 
idler rollers. This revolves the spool clockwise, 
thus rewinding the strip, and its speed may be 
controlled. A pear-shaped pendulum attached 
by a string to an eyelet screw in the upper 
upturned arm of the frame lies centrally between 
the idler rollers and in vertical line with the 



■'Plumb Bob Jo'ini 
allowing movemeiri- 
in one plane only 

■Seqmeni fastened fo. 



Degrees 
307010 
I5|5 




Feet 
120 
240 
360 

480 
600 

720 

840 

960 

1080 
1200. 
1320 
1440 
1560 
1680 
1800 
1920 
2040 

2160 
2280 
2400 
2520 
2540 
2760 
2880 
3000 

3120 



,-5 olid Cylindrical 
Weight aciing as 
Plumb Bob 



Pulling' 
Out 



■Pen 



Fig. 113. 
Fig. 113. — Sketch showing method of transferring plumb-bob 
motion to the pen. 
Fig. 114. — A record with Kinley's apparatus. 



Fig. 114. 



174 DEEP BOREHOLE SURVEYS AND PROBLEMS 

zero line on the record paper. It is the inking device, 
for in the lower end of it is a pen resting on the 
horizontally extended paper below. When the hole devi- 
ates the recording unit swivels on its pivots in the housing 
so that the weighted side comes to rest on the lower side 
of the dip when the boring tool to which the whole is 
attached is at rest. The pendulum swings inward and 
the movement of the pen is here governed by a toothed 
segment (Fig. 113) whose teeth mesh in the sliding arm to 
which the pen is attached. Figure 113 shows the cylindri- 
cal bob securely fastened to the segment.^ When the 
bob moves inward the pen moves outward to maintain its 
contact with the paper. The paper is divided into 5-deg. 
spaces by vertical lines so that when the instrument is 
vertical the pen rests on the zero line, the degree of accuracy 
being claimed as greater than that of the acid-bottle 
method. As the apparatus is run into the hole its body will 
swing around on the ball-bearing end pivots or sockets, 
and the pen arm and segment will swing as the plumb 
sways with the motion. Thus we get the jagged hori- 
zontal lines observed during each reading and during the 
''pull out" shown at the bottom of Fig. 114, which is a 
half-hour record from a well in the Little River Pool in 
Oklahoma. No calculations are needed when the record 
comes out of the hole. The whole is protected by a suit- 
able steel case. It is secured to the working tool in the 
hole, i.e., bailer, sandpump or drill pipe and read at each 
extraction of these. It suits 6^^ or 8-in. casing. 

^ By the courtesy of Oil Field Engineering, issue of Sept. 1, 1929. 



CHAPTER VIII 
PHOTOGRAPHIC METHODS 

Introductory Note. — In this group we include most of 
the accepted methods wherein a photographic record is 
provided of 

a. The actual walls of the borehole or the core outside 
the apparatus. 

b. The positions of various mechanical or electrical 
devices inside the apparatus. 

A vast amount of the world's boring is done by churn 
drills and other percussive drills yielding just the sludge 
of the percussion for examination at the surface. Even 
core drilling, which is about three times as expensive, does 
not always yield complete cores, owing to cavities and fri- 
able strata. Again the computation of dip, thickness, etc., 
obtained from the material produced by the drill tool suffers 
in direct ratio to the discrepancies due to the above geo- 
logical causes. 

An actual photograph of the borehole walls will remedy 
this defect and also supplement any faulty evidence. When 
the deposit is crystalline, as in certain copper, zinc, and 
salt deposits, little experience is needed to translate the 
photographic evidence and the same applies to marked 
geological changes shown in the photograph. In amor- 
phous deposits and those of massive regular texture more 
experience must be acquired in order that one may (if 
possible) decipher the data presented by the film. 

Photographic records of mechanically or electrically 
controlled devices, or those depending on gravitational 
action will be easily comprehended by any intelligent 
person. All photographic records are well suited to con- 
tinuous recording in and out of the hole. They are coming 
more and more into favor for very deep holes, the multiple 

175 



176 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



photographic apparatus having already achieved some 
remarkable surveys. 

The first interior photographic device was that of Oehman 
in 1905 in which shadows of a needle and plumb bob oppo- 
site electric light globes were recorded on a sensitized 
paper. The first device for photographing the borehole 
walls was that of Atwood in Wisconsin, in 1907. 

Atwood's Apparatus. — This, the first external photo- 
graphic device for boreholes, was invented in 1907 by J. T. 
Atwood of Wisconsin University. The camera a (Fig. 115) 




Fig. 115. — Camera, tripod and lowering reel. 



is mounted in the lower end of a watertight tube b, 5 in. 
outside diameter and 43 in. long. Near the upper end of 
the tube a plate-glass window with a mirror c behind it is 
mounted so as to reflect the image of an object placed 
before the window directly down the tube and into the 
camera (Fig. 116). On each side of the mirror is mounted 
an electric lamp d with a reflector, which sends the light 
through the window and also prevents any light from 
shining directly into the camera. 



PHOTOGRAPHIC METHODS 



111 



This iron tube, or camera tube, is lowered and raised 
in the well by a cable winding of the lower of two drums e 
and / (Fig. 15). The upper drum / carries an electric 
cable to operate the lamps and to turn the camera film. 

The cable is so fastened to the tube that the window 
will come close to the wall of the well, and, with the lights 




Fig. 116. — Atwood's borehole camera with parts removed to their relative places 

outside the case. 



burning, the wall is brightly illuminated. In making an 
exposure with a No. 16 stop the lights are turned on for 
about 20 sec. Before making a second exposure the 
camera is lowered or raised 43-^ in., the 
distance covered by one photograph, 
and a new part of the film is turned 
into place by making and breaking the 
circuit of an electromagnet acting upon 
the roll of film. In this way a series of 
50 or more photographs can be taken at 
the rate of 1 a minute, and they will 
show a continuous strip of the wall for 
a distance of 20 ft. or more. The win- 
dow, which is 13^^ by 5K in. is set in 
litharge cement. A guard strip is riv- 
eted to the tube on each side of the 
window. The hoisting cable is attached 
to the hook g, 4 in. behind the window, 
so that in the ordinary 6-in. drill hole the 
window always hangs near the wall. The 
mirror, lamps and reflectors are mounted ^^g- ii7.— Camera 

. , T , 1 y^^th. side removed. 

on an oak plate, which can be adjusted 

to bring the mirror in the right position behind the window 

(Fig. 117). The two lamps are 10 volts and 5 cp. each. 




178 DEEP BOREHOLE SURVEYS AND PROBLEMS 

The camera is 32 in. long and 3^{ e by l^i in. in cross- 
section. It is fitted with a 9-in. Bausch & Lomb rectilinear 
lens. The camera^ is so placed in the tube as to photo- 
graph the 4:}^ in. of wall reflected in the mirror upon 3^^ in. 
of film, the maximum length obtainable with a width of 
film of 1^^ in. This reduction gives a photograph eight- 
tenths full size. 

The camera is fastened in the tube by two thumb screws. 
One side of the camera is fitted in grooves and is easily 
removed for changing the film. The film winds from the 
end roll i (Fig. 117) across the flat plate for exposure and 
is wound upon the other roll j by the operation of the 
electromagnet h (Fig. 116) acting through an arm and 
pawl upon a ratchet wheel. The wires for the coil have a 
plug connection at the bottom end of the camera. A 
three-core cable of No. 14 wire and 250 ft. long carries 
the current from four small double-storage cells. A resist- 
ance coil is used to adjust the voltage for the lamps before 
lowering the camera tube. Connection from the cable 
to the battery and switches is made by a triple plug in the 
end of the shaft of the winding drum. The hoisting cable 
is a heavy line of small twisted wires, tested to over 500- 
Ib. tension. The drum is wound with 300 ft. of this 
cable, and has length tags soldered to it at 5-ft. intervals. 
The ratchet on the drum has a double pawl permitting of 
3-^-in. changes in the position of the camera tube. No 
attempt has been made to record the direction in which 
the camera hangs. This could be done by an orientating 
coupling rod or by mounting a magnetic needle to show 
in the photograph. Good photographs can be taken in a 
well hole both above and below water. The camera has 
been operated in a 200-ft. prospect hole 6 in. diameter 
upon the Vinegar Hill Mining Company's property, about 
7 miles north of Galena, Illinois, at a depth of 162 to 200 ft. 
when the water stood at about 85 ft. from the surface. 

The first attempt in taking photographs under water 
was entirely successful. The camera was filled with air 

1 Eng. Min. Jour. Press, p. 944, May 18, 1907. 



PHOTOGRAPHIC METHODS 179 

dried by forcing through sulphuric acid. After lowering 
the camera tube into the water it was raised to the surface 
to see if in cooling any moisture had been precipitated 
on the inside of the window. The window was found to be 
dry and clear, and upon lowering the second time, the expo- 
sures were made without any regard to the location of ore 
bodies. The device is now chiefly of historic interest and its 
limitations are obvious, however its principle still survives 
vigorously. 

Reinhold's Photographic Apparatus. — This device was 
invented in 1924^ by Thomas Reinhold, Chief Geologist 
of the Geological Survey Department of Holland, and 
described at the International Congress of Geology at 
Madrid in 1926. 

Its purpose is to provide a photographic record of the 
strata pierced so as to obtain the nature of the same, 
detect the presence of fissures and to get the dip of the beds. 
It will be seen to be additional to ordinary core orientation 
or borehole deviation methods, since it photographs the 
walls of the unlined part of the borehole. 

The apparatus shown in Figs. 118 and 119 is attached 
to the upper end of the drill rods and then lowered to the 
required spot in the hole. It will be noted that a section 
of the hole is isolated in a watertight manner at the upper 
and lower ends by means of the packing rings x and y. 
This length of the borehole is then washed out by means 
of clean water, the wall is illuminated, and a photograph 
is taken. The photographic apparatus is enclosed in a 
strong bronze tube between the packing rings, the film 
camera being placed in the chamber h. Two electric lamps 
/ illuminate a part of the wall g. The rays of light pass 
through the glass and are reflected upward from the reflector 
d to the lens c, throwing an image on the film k in the 
camera. A small electric motor a changes the exposed part 
of the film for a fresh one after each exposure. Enough 
film is provided for obtaining a few hundred exposures, one 

^ British Patent No. 226,079; see also Colliery Engineering, p. 371, August, 
1926. 



180 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



after the other, simply by moving the instrument and 
switching on the light. 




Fig. 118. — Instrument in borehole. Fig. 119. — Arrangement for large bore- 
holes. 



Electricity is supplied by a cable j running from a 
switchboard at the surface and located at a convenient 



PHOTOGRAPHIC METHODS 181 

place near the borehole. A transformer within the instru- 
ment is provided for reducing the tension of the electric 
current. Current at, say, 220 volts, is used to transmit 
electricity in the long cable with little loss, and it is reduced 
to lower tension for easier manipulation in the instrument. 
An automatic switch is introduced to make the connections, 
such as switching on the motor or the lights. 

The clean water is injected through the tube h, and the 
mud-laden water is forced out through the aperture i. 
This arrangement enables the apparatus to be employed 
in mud-laden boreholes by replacing the dirty water with 
clear water. In the case of oil wells, where an oily film 
on the object glass would interfere with the photograph, 
it has been proposed to wash with benzine instead of water. 
By changing the rubber packing rings x and y the same 
instrument may be employed in boreholes varying from 
5>^ to 12 in. in diameter. 

Near the lower end of the instrument a compass needle e 
covered with a graduated disc is placed. A small lamp I 
throws light on this disc, so that part of it is photographed 
at the same time as the principal photograph is taken, the 
rays passing by the side of the mirror d. In this way 
the direction of every face of the rock is recorded on the 
photographs. 

In operating the apparatus it is lowered from the drill 
pipe to the depth at which information is required. Clear 
water is then turned on, and in about 10 min. the original 
slimy water is replaced, the view being then clear enough 
to start photographing. This is done by switching on the 
light for 10 or 15 sec. The film is changed by drawing it 
through the camera by means of the motor, and another 
photograph may then be taken. The instrument may be 
turned round so as to cover the whole of the circumference 
of the borehole with six or eight exposures, according 
to the diameter of the hole ; in a 6-in. hole six exposures are 
sufficient, but in larger holes eight or more exposures are 
required. The instrument may be raised or lowered to 
photograph fresh sections. A good idea of the walls of a 



182 DEEP BOREHOLE SURVEYS AND PROBLEMS 

borehole is obtained from about a hundred or so photo- 
graphs, which may be taken in a comparatively short 
time. 

According to a recent note from the western oil fields 
of the United States, this apparatus has yielded valuable 
information in the region of Signal Hill, in the western 
mineral field. A suite of very instructive photographs 
taken by the inventor and showing fissures and natural 
water veins have appeared.^ 

The device has the advantage that the less expensive 
percussive boring can under certain conditions be made 
to yield as valuable geological data as a core-drilling plant. 
Again for finished holes with no cores available it will 
provide information which could not otherwise be obtained. 
When "torpedoing" well bases to increase the yield the 
shattering effect can be photographed. It can also be 
used for the inspection of casing as to corrosion, buckling, 
unscrewing, collapse, etc., and for the examination of 
cemented linings; also for locating lost or broken tools. 

Its great drawback as a deviation instrument is that in 
strata thickly bedded or without stratification planes or 
other marked features it has nothing to photograph. It is 
Umited to the size of hole it will suit and can only be used 
for orientation purposes in unlined holes. 

Oehman's Apparatus. — This is a magnetic needle and 
plumb-bob photographic device which has been extensively 
employed in the deep reef boreholes of the Rand and else- 
where. It was first invented by Oehman about 1905 and 
later improved upon by A. Payne-Gallwey.- 

From Fig. 120 it will be seen to be a non-magnetic tube 
a in two halves connected by a coupling 0. The magnetic 
needle b is in the lower half with an independent plumb 
bob c, each swung over a gimbal d with a small electrical 
lamp e above each. These are held in position and pressed 
against a brass insulating rod /in the middle of the coupling 

1 Colliery Engineering, p. 372, August, 1926. 

'■^ Hatch, Dr. F. H., A paper read before the British Association, see 
Brit. Assoc. Rept., 1905. 



M, 



Photographic methods 183 

by a spring g attached to the bottom screwed plug 
/i.i A series of screws i in the side of the tube in 
straight parallel lines project inward about 3^f e in. 
There are slots down the cylindrical cases carrying 
the lamps, and the needle and bob, the screws i 
acting as guides for these slots. 

A dry battery k and clock j with spiral spring I 
attached are in the top half of the tube. This 
spring I assures contact when the two halves are 
screwed together by pressing on the top end piece 
m. This latter has a ball-bearing swivel n for 
attaching the wire for lowering if needed. 

The vulcanite cases p carry the brass marine 
compass attachments for the magnetic needle. 
The plumb-bob attachment is also vulcanite for 
insulation purposes. The compass swings in rings. 
On the face of each gimbal is a fixed pin point and 
round the edge is a recessed ring which holds the 
disc of sensitized photographic paper in place, the 
pin points holding them in position. The plumb 
bob is made of gold attached to a fine silk thread 
swung from the center of a thin disc of plate glass 
q, which fits into a recess in the tip of the vul- 
canite case. 

Both the magnetic needle and the plumb bob 
swing immediately above (almost touching) the 
sensitized papers. A copper lug s attached to the 
extra wheel r of the watch makes, at a certain 
time, connection with a copper spring t attached 
to the frame of the watch and so completes an 
electric circuit lighting the lamps above the bob and 
needle. Now a sharp shadow of each is photo- 
graphed on the sensitized paper; these are devel- 
oped to give dip and direction by making the pin 
pricks coincide, as shown in Fig. 121, where the 
hole dips 25 deg. in a direction N.20°E. (magnetic). 

^ ® V & y Pjq J20. 

1 Hoffmann, J. I., Recent Practice in Diamond Drilling and {After Hoff- 
Borehole Surveying, Trans. Inst. Min. and Met., April, 1912. mann.) 




184 DEEP BOREHOLE SURVEYS AND PROBLEMS 

This method was used to survey a hole in the Heidelberg 
district of the Transvaal which ultimately deviated 58 
deg. off the vertical, the hole being 6,656 ft. deep. A 
special pilot wedge device (Fig. 122) 2 in. in diameter 
and 18 in. long with oblique face 6 in. long was first lowered 
(wedge face upward) and its being solid on the floor 
assured by letting down the rods. Another rod 3 ft. long 
screwed at both ends was used to get the wedge position. 
This last rod (Fig. 123) had a spiral spring on one end 
and a 2-in. cup with a M-in. diameter brass pin through it 
at the other end. This cup was filled with lead which 
projected about 1 in. beyond its edge and turned to its 
diameter. The end of the rod with the spiral spring was 

Pin T^ P'"'^^^ 

Prick I ^ Prick . \ 

Fig. 121. 

screwed into the instrument base instead of the lower plug. 
The top end of the instrument was screwed into a brass 
tube 10 ft. long and then again screwed to the ends of the 
drill rods. It was then lowered in on to the wedge. 

A chisel cuts an impression in the lead, a photograph 
being taken of the magnetic needle at the same time. 
A disc of lead is sawed off on gaining the surface and the 
direction of the wedge calculated. The guide wedge 
(Fig. 124) is an exact counterpart of the pilot" wedge and 
is screwed into the said main deflecting wedge, which is 
solid, 2 in. in diameter and 7 ft. long. These wedge 
devices are not an essential part of the equipment but are 
added because they enable other sections of the reef to be 
taken in the same borehole, saving the expense of extra 
holes. 



PHOTOGRAPHIC METHODS 



185 



Many successful borehole surveys have been made with 
this apparatus and W. Gallacher, the inventor of the 
instrument illustrated in Plate VIII, added to the above 
ancillary devices various means for obtaining successive 




y. 



I 



Fig. 123. Fig. 124. 

Fig. 122.— PUot wedge. 

Fig. 123. — Payne-Gallwey's wedge surveying attachment. 
Fig. 124. — Guide wedge. 

deflections in the same hole. It was also a wedge device. 
Mr. Hoffmann^ gives several instances of its successful 
application. 

1 Op. cit., p. 9. 



186 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



Haussmann's Apparatus. — This apparatus was invented 
by Prof. Karl Haussmann at the Technical High School in 
Aix la Chapelle in 1907. It is essentially a double magnetic 
needle, spirit level and photographic device and has com- 



Surface 



6160, N50E 
603O'N4O°E- 
5900M44°E-: 
5812'' ■ 

5500'; 




'6050'4 5° 

, ,„ 6l60'45°Bo-HomofDeflecfion 

6600^8 
&656'°gof fo^ of'fiole 

Fig. 125. — Course of a South African drill-hole, vertical and horizontal views. 
{After J. I. Hoffmann by permission of the Institution of Mining and Metallurgy, 
London.) 



manded such respect for a long time on the Continent 
that we shall enter into some detail regarding it. 

Figure 126 shows the assembled plumbing cylinder with 
guide springs and an attachment for the core cather below 
and one for the rope or rods above. The conductor cable 
runs along the rods and down into the interior of the cylin- 



PHOTOGRAPHIC METHODS 



187 



der. On the right is an accumulator with cells and on the 
left, on the tripod, a current switch connected to the accu- 
mulator and coupled to the cable reel. 

The 'plumbing cylinder has a non-magnetic casing 40 
mm. wide, 10 mm. thick and 750 mm. long and is in three 




Fig. 126. — Haussmana's apparatus assembled. 

parts; the lower one for taking the plumbing apparatus, 
the middle one the registering apparatus and the upper 
one the connection to the electric conductor. At the ends 
of the middle section are two corresponding graduated 
circles divided into 10-deg. intervals; the two other sections 
carry reading marks. The upper mark lies in the plane 
of symmetry of the suspension device and the lower one 
corresponds with channels in the lower casing in which 



188 



DEEP BOREHOLE SURVEYS AND PROBLEMS 





Fig. 127. 



the plumbing frame with the registering apparatus is 
inserted. Thus one can screw up the casing 
without nut surfaces and still if needed be 
able to read the position of the registering 
apparatus against a guide rod.^ 

The Guide Springs. — The longitudinal guides 
above and below the cylinder are of steel and 
ringed at their ends, the rings being rotat- 
able about the plumbing cylinder. The outer 
ring can be adjusted up and down it. These 
springs (Fig. 127) must act simi- 
larly together so that the most 
outer points always lie on a 
conical surface through the axis 
of the apparatus. 

The Inclination Measurer. — 
Figure 128 shows the internal 
construction of the dip meas- 
urer. One of the three bars 
forming the frame has a lamp 
(4 volts, 0.45 amp.) with a 
reflecting parabolic mirror h 
below it (Fig. 128). The side 
conductor wires leading up from the lamp are 
well coiled about one another in order not to 
influence the neighboring magnets. Next 
above the lamp is a plain glass plate c with a 
swinging magnetic needle d held by arm e. A 
Httle above this an adjustable level / is pro- 
vided with a glass floor on the cover of which 
a second magnet swings. The glass plate may 
be removed so that both magnets, oppositely 
influenced, may give a suitable intersection 
angle. Above the level on its glass cover are 
concentric rings 2 mm. apart, then come the 
lenses g and h (Fig. 128). Some convex 

1 Gliickauf, No. 7, p. 233, Feb. 15, 1908; Mitt. Markschei- 
derwesen, Heft 9, p. 53, 1908. 





PHOTOGRAPHIC METHODS 



189 



lenses can also be set here. On the upper surface of the 
level is a mark a a (Fig. 129) representing the abscissa 




The 



Fig. 129. 

axis on which the direction of the throw is taken 
two convex lenses g and h from 
which the latter is screened throw 
the image of the level with the con- 
centric rings, the abscissa axis, and 
the upper needle ns (Fig. 129) on to 
a sensitive paper strip i (Fig. 128) 
working on rolls Ri and jB2 and 
shafts r, r. This is the headpiece 
with registering device shown in Fig. 
128. Below the frame (not visible 
in Fig. 128) is a central lug for stick- 
ing in the casing. There are connec- 
tion screws for the level and the 
whole frame, for connection and 
screwing in the frame to the cylin- 
drical casing. 

The Registering Apparatus. — This 
is shown in Fig. 130 on a greater 
scale than in Fig. 128. A long strip 
of paper very sensitive to light winds 
from a roll Ri over two guide roll 
shafts r in the image plane of the 
level and lens system. From here it 
runs on over the fixed drive roll R2. 
There is a solenoid e above the rolls provided with a clutch n 




Fig. 130. — Haussmann's 
registering apparatus. 



190 DEEP BOREHOLE SURVEYS AND PROBLEMS 

which engages in a cog wheel z on the upper roll. If the cur- 
rent to the solenoid is shut off the core rises and the clutch 
turns the upper roll one tooth further, thus drawing the 
paper strip a corresponding piece forward. On interrup- 
tion of the current the clutch is snapped into the next 
tooth by a small spiral spring/. The base of the registering 
device is fitted exactly to the end plate of the plumbing 
frame. 

The Current Supply. — The conductor wires go from the 
lamp and solenoid to three concentric measuring rings 
which are in the cover of the registering apparatus insulated 
from each other. One of the rings is connected to both 
the lamp and solenoid. From here on the cable is led 
into the upper part of the casing and terminates in three 
spring rods sliding on three rings in the cover of the register- 
ing device when screwed up. This gives an easy connec- 
tion between cable and lamp or solenoid. From the rods 
the cable goes through the neck of the plumb cylinder 
casing with suitable screw nut tightening and protection 
from water. It is a three-wire cable, but two will do if a 
suspension rope is used or rods, and, if there is a reversing 
device, one will do. 

The Switch. — This apparatus is switched in between the 
source and the cable roll. It is used for cutting off, inter- 
rupting, regulating, and reversing the current. It carries 
a variable resistance in a wooden frame with an ammeter 
and voltmeter between, which is an attachment for switch- 
ing in a control lamp in the circuit. The plugging arrange- 
ment is for closing or reversing the current to either the lamp 
or solenoid of the plumbing apparatus. There is a press 
button for the supply to the lamp as well as a moving 
measuring arm which slides over a toothed measuring 
plate which has spaces filled with a non-conducting 
substance. 

A numbered rotating ring is fitted for the number of 
teeth. The plate is connected to the registering apparatus. 
If the accumulator is switched in and the arm turned the 
registering roll turns correspondingly. The functioning 



PHOTOGRAPHIC METHODS 



191 



1 



^ 



E 



m 



Fig. 131. 



of the apparatus depends on the action of the solenoid 
armature. 

The Guide Rods. — If magnetic orientation fails, as, for 
instance, with lined holes, a mechanical means must be 
resorted to for obtaining a definite direction, 
and his is done by means of the guide 
rods. These are made of stiff-membered 
cross links as in Fig. 131. In the end of 
equal lengths of tube taps are fitted which 
are crosswise to one another and have 
alternate interior and exterior guide surfaces. 
The several members are bolted in right- 
angled planes immovable; thus the rods can 
press against a winding borehole without 
turning their members in shear. Over the 
borehole the guide jack or trestle is set up 
which gives a definite orientation to the rod 
members as they are let into the hole and 
for adding fresh members. Haussmann used members 75 
cm. long, 1 cm. thick, and 4 cm. wide, strengthened above. 

The Level. — The level is used instead of a plumb bob 
and cuts out much inconvenience; the plumb oscillates a 
lot and slowly comes to rest and is also not so exact as the 
level in such a narrow space. The level on the other hand 
comes to rest quickly and its sensitiveness is quite inde- 
pendent of the length of the plumbing cylinder and no 
magnification of readings is necessary. 

The Crossed Magnets. — Magnetic needles are suited to 
undisturbed regions, unlined holes, and iron-free places, 
but one has no control over a magnetic needle. Two 
needles close together, swinging in parallel planes, cross 
when under contrary influences; we thus have a means 
of locating disturbances and preventing false readings. 
If a magnetic deflection is present the cross angle of the two 
magnets will vary and on the vertical turning axis of the 
magnetic needles is a differential variometer for horizontal 
intensity. In some cases cutting out faulty orientation 
survey spots will not give a correct notion of the survey 



192 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



as a whole, and in such cases mechanical means must be 
used. 

The Mechanical Guide of the Rods. — The above-mentioned 
rods of stiff members with cross links are movable on all 
sides in their long axis but not at all in the cross direction, 
so that they can follow a winding hole without losing their 
orientation. Thus the borehole course is resolved into 
short pieces. The correct working of these guides is an 
important preliminary of all surveys. Trial of rods 
through 180 deg. before every test is considered a good 
check. 




Fig. 132. — Borehole survey by Haussmann's method. 



In plumbing a hole in undisturbed conditions, first 
arrange marks for depth measurements on the rope or 
use a measuring wheel, or, if using rods, mark the rods for 
a given direction on the scale of the registering apparatus. 
Now when ready switch in the resistance for the lamp and 
solenoid and read with the ammeter and voltmeter. The 
first survey is made with the plumb cyUnder hanging 
free in the hole. By means of the switch lever we can 



PHOTOGRAPHIC METHODS 193 

bring a new piece of photographic paper strip into the 
picture plane and by pressure on the middle button of the 
switch box illuminate the lamp. We have now to get 
the depth which is got from the rope or rods and in this way 
can carry out hundreds of surveys without pulling the 
plumbing cylinder out of the hole. A dark room is impro- 
vised in which to develop the sensitive figures of Fig. 129. 
The results can be evaluated by means of a polar coordinate 
scaler or a rectangular coordinate tracer. 

Figure 132 shows an actual survey by this method of a 
borehole with a 2.9 per cent deviation off vertical, the small 
circles being the horizontal sections of the borehole at the 
respective depths in meters, the axes numbers being the 
lateral displacement in meters. 

For Haussmann's apparatus the following advantages 
over previous devices have been made and they appear to 
be well founded: 

1. A higher degree of accuracy is obtained with a sensi- 
tive level than with a plumb bob or pendulum. The level 
permits of a reading accuracy of 0.1 to 0.01 per cent. 

2. It provides a sure reading in magnetically disturbed 
regions, giving reliable direction determinations. 

3. Repeated measurements can be made, each giving a 
sharp photographic indication. 

4. Good centering. 

5. Simple and rapid assembling and measuring, which 
holds also for great depths. 

Owens's Apparatus. — This is an illuminated clinometer 
and compass device, invented by Dr. J. S. Owens in 1925, 
and having an external and internal casing like Gallacher's 
apparatus. The inner one bearing two corner tubes is 
free to rotate on the long axis pivots. This, of course, 
keeps the inner casing with the clinometer and compass 
always swinging into the vertical and horizontal planes, 
respectively; the other inner carrier tube holds mechanism 
which controls the length, number and interval of expo- 
sures. This mechanism is a clock-operated controller 
making and breaking circuit with electric lamps. The 



194 DEEP BOREHOLE SURVEYS AND PROBLEMS 

clinometer is an eccentrically weighted drum bearing a 
strip of sensitized paper which rocks close to a diaphragm 
with apertures in it. 

The magnetic needles and apertures move on one spider 
and they are encircled by a strip of sensitized paper on a 
drum and all hght is excluded except at the apertures. 
On top of this is an opal glass lit up by the lamps which 
flood the inside with subdued light, and this gives the 
photographic record of the needles. When horizontal 
each lamp lights up half of the dome, and when the instru- 
ment is vertical one lamp lights up the whole dome, so that 
illumination is constant at all angles. The instrument is 
best understood if taken part by part.^ 

Figure 1 (Plate XII) shows the complete instrument. 
At the ends of the external casing 3 are screwed two similar 
watertight plugs 1 and 55 of non-magnetic material, 
the latter having the hauling rope eye. The two separate 
internal carrier tubes 5 and 39 are bayonet jointed for easy 
removal. In Figs. 1 and 2, on pivots 6 and 21, is a cradle 
26 with a compass, clinometer and two lanterns. By way 
of cap bolt 21 a stud 25 makes electrical contact with a dry 
battery. The weight of the cradle 26 keeps the clinometer 
in a vertical plane, as in Bawden's method. It is borne 
on end pivots 7 and 19, and there are two lamps at 35 on 
the central line of the cradle in front of and behind the com- 
pass, the one always throwing light on the clinometer 
holes. These lamps are connected in parallel to bolts 20 
and contact finger 57. 

The clinometer 27 (Figs. 2, 3) is a drum on a spindle free to 
revolve at right angles to the cradle pivots and has oil 
damping in its bearing sleeves; and behind are spring clips 
9 for the record paper 10. On its side next to the compass 
is the aperture plate 11. 

The magnetic compass is spherical and borne on pivots 
63 at right angles to the cradle pivots (Figs. 2, 4). Its 
lower half 33 is sohd, thus being the righting weight which 

1 Dr. J. S. Owens's paper read before the Institute of Mining and Metal- 
lurgy, Jan. 21, 1926. 



PHOTOGRAPHIC METHODS 



195 




196 DEEP BOREHOLE SURVEYS AND PROBLEMS 

keeps it horizontal, and the upper half 15 is a hollow dome. 
In an annular recess inside the bowl 33 is a strip of sensitized 
paper fixed relative to the bowl in which the needles move. 
The needle pivot in the bottom part of the bowl 33 holds 
the needle, which is a standard sewing needle, on carrier 
62. There are four of these rectangular needles; two 30 
flat, and two 31 on edge on the bearing spider 29. This 
spider has two opposite holes at right angles to the center 
lines of the needles, and two white paper reflectors 65 
opposite the holes. In the cradle on the compass side of 
each lantern is a diaphragm 34 (Fig. 2) with a bell-mouthed 
hole with clip held screens. A number of screens of tracing 
cloth are placed in these to adjust the intensity of light 
on the dome. The compass has a sliding cover 13 over 
the upper half and is finished dead white inside for even 
lighting. This all provides uniformly diffused light of 
suitable intensity within narrow limits. 

The controller is for determining the length and interval 
of exposures which may be two or four per hour, dependent 
on the setting of contact finger 44. A control screw 50 
(Fig. 1) insulated from the control base 49 is prolonged into 
a spring plunger 38 by means of which a good contact is 
made to the dry battery. Owing to the high-pitch, left- 
hand thread on this small diameter screw the drum retreats 
from the clock when it is revolved by the crank. This 
crank is fixed to the minute-hand spindle of the clock and 
drives the drum through the insulated pin 50 projecting 
from the spider 52 carrying drum 51. This drum has four 
longitudinal metal contact strips 45 in electrical connection 
with the spider for giving two or four exposures per hour. 
The circumferential width of these strips is such that a 
series of exposures of increasing length are got during each 
revolution of the drum, and this enables the records to be 
identified. The drum contacts, as shown by the finger 44, 
on slide 41. 

At the end of carrier tube 39 is the clock 48 with its minute- 
hand spindle extended to carry a crank 47 with a milled 
setting knob 54 on opposite ends. It is readable from the 



PHOTOGRAPHIC METHODS 



197 



opening over the controller. The standard dry battery 37 
in carrier 39 bearing on plunger 38 presses its central stud 
on to the contact bolt 21. 

The insulation rod 59 (Fig. 5, Plate XII) is attached 
when the instrument is in use and coupled to the drill 
rods or rope for lowering. Before making the survey 
the device is taken to a dark room where the two carrier 
tubes are taken out and uncoupled and record strips of 
bromide printing paper are fitted to the clinometer and 




Magnei-i'c 
Needle 



Inside View from above of Compass Apertures and Needle 
Fig. 133. — Inside view of compass apertures and needle from above. 



E 



No.l 






±_1. 



(Daiutny^^' 2^J (Oaiumyi^-I 



(c) 



Kh) 



No-2 No. I 2 ; 

(Daiurn) (Dcrlum) 






90° 45° 0° 45° 90° /J5° 180° BS" 90° 



id) 



Fig. 134. — Compass record. 



compass drums. The datum record from which deviations 
are measured is arranged in the dark room, this being a 
standard datum such as the horizontal instrument casing 
with the controller end toward the magnetic north. Now 
set the record strips with controller to give one exposure and 
reassemble the carrier tubes in the casing. After time 
sufficient for exposure the controller automatically stops and 
it is taken to the hole to be surveyed when the controller is 
reset. The eyed plug 55 is now unscrewed and the carrier 



198 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



tube withdrawn sufficient to expose the controller, which is 
set for the desired number of records and required interval 
between time of setting and first exposure. The watch 
of the operator is synchronized with the instrument clock 
and the whole apparatus assembled, screwed up tight, and, 
with the insulation rod attached to the instrument, lowered 
to the spot to be surveyed. Depth and time are noted, 
and time for exposure at the spot exceeded, it is lowered 
to the next spot and so on for the number of spots being 




C.L.of Clinomeier 
Drum Spindle 



OLrtsideFrontViewof Clinometer Apertures 



30° 



Nol- 



-fJo.l 



No.2- ■=- 
(Datum) ' 



A/o.2 
■No.2 i 



Jo I 



45° 



45 



90 



(a)| I (b)| I I |Cc) 

Topical Record 

showing progressive 

increase in Dip 

Fig. 135. — Clinometer record. 



surveyed, after which the instrument automatically ceases 
working and is withdrawn from the hole. It is now taken 
to the dark room where the record strips are withdrawn and 
developed. 

Assuming that the instrument is horizontal and the con- 
troller end points toward the magnetic north, which is 
datum line direction, we get a record as in Fig. 134a. 
If the said end be pointed northeast, the record is as in 
Fig. 1346; if southwest, it would be as in Fig. 134c, the dis- 
placements being typical for these positions. The drums 
are designed so that 300 deg. equals 3.6 in. on the record 
strip surface, or 1 deg. equals 0.01 in. Thus by dividers 
and a diagonal scale we may read hundredths of an inch, 



PHOTOGRAPHIC METHODS 



199 



as seen in Fig. 134d, where distances h, c and d are for 
records 2, 3 and 4, respectively. Similar reasoning applies 
to Fig. 135 showing clinometer records. Figure 136 shows a 




494.5/ ^j. jniended Course ofHole_ 

494.5'^'Jy]'j.~iJ)r,r-Course265'?60' 200' of Hole 30^ 
Z20°Acfual4m ^""' 79^794° ?92 293 



289.5 



29i°294'' 292" 293 

P I d n 

Fig. 136. — Actual survey of a Portuguese borehole. 



typical borehole survey from Portugal constructed from 
such records. We are indebted to the proprietors of 
Engineering, and C. F. Casella & Co., London, the makers, 




Fig. 137. 



for the photographic views showing (Fig. 137) the compass 
and chnometer, (Fig. 138) the casing and inner parts ready 
for assembly and (Fig. 139) the clinometer and contact 
drum. 



200 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



Anderson's Apparatus. — We have had no personal oppor- 
tunity of examining this method, the full details of which 




Fig. 13S. — Compass and clinometer. 



are not accessible. However, it is known to be another 
application of the orientated drill-stem method, the survey 




Fig. 139. — Clinometer and coutact drum. 

principle being that of the multiple-photograph method 
wherein one or more pendulums are photographed for 
each position. It has been widely and successfully 



PHOTOGRAPHIC METHODS 



201 



employed in California. It is about 2>yi in. in diameter 
and about 7 ft. long (Fig. 140) and is capable of taking 88 
records each trip, the distance between each setting being 
at the control of the operator. The survey can thus be 
made in a normal round trip and usually at the rate of 1,000 
ft. in 70 min. 





Fig. 140. — Anderson oil-well Fig. 141. — Demonstration frame with 

survey apparatus about to be the machine set for certain inclination 

lowered in hole, with stands of from the vertical, 
drill pipe set back in the derrick. 



The apparatus, including the pendulums, photographic 
equipment, timing and actuating devices, is all contained 
in a watertight welded casing which is constructed to 
be run into the well on the end of a string of drill pipe or 
tubing. Thus it can be used in mud and water. It is 
generally run on tubing or drill pipe, although in the case 
of one Pan-American well it was run on a sand line. In 



202 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



Anderson's sand-line method a set of expansible steel-spring 
guides is run both above and below the instrument in its 
shell to prevent rotation in azimuth. A practically 
frictionless swivel connection is made from the end of the 
sand line to the instrument container. 

Readings are taken at each stand length and the station 
distances measured on the drill lengths, the operator taking 
the instrument as delivered from the well and interpreting 




Fig. 142. — Plan of very deep borehole surveyed by Anderson. 



the results on a special orientating stand (Fig. 141). 
Orientation is thus measured mechanically the direction 
of drift being referred to a north-south line on the derrick 
floor so that at each exposure the directional deflection 
is known at the surface. 

Interpretations will average within about 7 ft. of arc 
of being correct for vertical angles and 30 ft. for azimuth. 
The instrument is also self-checking in that all recorded 
points must fall on a curve when plotted. Various surveys 



PHOTOGRAPHIC METHODS 203 

with this instrument have been pubUshed,^ while Fig. 
142 shows the course of the first 6,948 ft. of the deepest 
well as surveyed by this device. Goodrich^ quotes an 
instance of one survey by this device in a well 6,522 ft. 
deep taking 6 hr. 45 min. 

1 Smith, F. M., Oil Gas Jour., p. 120, Dec. 2, 1926; Eng. Min. Jour. 
Press, Feb. 6, 1926; Anderson, A., Oil Age, p. 20, September, 1926. 

2 Oil Gas Jour., p. 38, Nov. 15, 1928. 



CHAPTER IX 

GYROSCOPIC COMPASS METHODS OF SURVEYING 

BOREHOLES 



Introductory Note. — The gyroscope being uninfluenced 
by local attraction is well suited to the survey of boreholes. 
The physicist, Foucault, whose pendulum researches are 
well known, instituted in the middle of last century the law 
that a spinning wheel with three directions of freedom, i.e., 
one which is free to move in all three dimensions, is unin- 
fluenced by the force of gravity and 
is suited to indicate the rotation of 
the earth. In order to have a freely 
moving wheel it must have Cardan 
suspension. In order that the action 
of gravitation be removed the three 
axes must all meet in the center of 
gravity of the system (Fig. 143). 
Such a gyroscope is called an azimuth 
gyroscope and then if no external 
force acts on it — whether at rest or 
rotating — it keeps its position in 
space unchanged. The term ''azi- 
muth gyroscope" is not happily 
chosen because the magnetic compass 
also has an azimuth, only this is not optional but zero 
(meridian) . 

Foucault has also shown that a gyroscope which is com- 
pelled to move in a horizontal plane endeavors to adjust 
itself to the north-south line. Such an arrangement is 
called a gyroscopic compass or gyrocompass. In England 
and France experiments have been undertaken since well 
into last century, with the purpose of utilizing the gyroscope 
as a compass. In Germany experiments have been under- 

204 




Fig, 



14 3 . — Wheatstone's 
gyroscope. 



GYROSCOPIC COMPASS METHODS OF SURVEYING 205 

taken mainly by the firm of Siemens and Halske. Owing 
to insufficient technical assistance and faulty knowledge 
these experiments were more or less abortive. 

A gyroscope^ consists of a heavy wheel mounted on bear- 
ings free to spin about different axes, usually symmetrical 
axes perpendicular to the equatorial plane (Fig. 143). 
When the conditions of dynamical symmetry are not obeyed 
we get bad static balance, as when 

a. The center of mass of the gyroscope does not lie 
on the spinning axis; as in the case of an eccentrically 
mounted disc. 

b. The principal moment of inertia is not coincident 
with the spinning axis, a torque being thrown on the bear- 
ings; as when we get oblique but central mounting. 

c. The moments of inertia about all axes through 
are not normal to the axis of spin; as when we have an 
elliptical centrally mounted disc. 

These are corrected mainly by distribution of small 
masses on the disc. When all the axes xx, yy and zz are 
as in Wheatstone's gyroscope shown in Fig. 143, it is said 
to be ''free," and if any one is locked it is said to be ''con- 
strained." This latter feature sets up certain phenomena 
applied in borehole surveys. 

Degrees of Freedom. — The spin of the disc about zz 
is known as the first degree of freedom, the rotation of the 
disc about yy axis the second and that about the xx axis 
the third degree of freedom. When the disc spins about 
zz there is an instantaneous angular movement of the axis zz 
known as "precession." It can be noted if a heavy 
cycle wheel is held vertically in front of the body with 
the left hand by means of an axle and spun clockwise 
with the right. The bearing pressure on the left palm 
tends to vanish and the wheel under the influence of the 
spin and gravitation rotates anticlockwise about the experi- 
menter's body. The free gyroscope tends to keep the axis 

^ Glazebkook, Sir R., "Dictionary of Applied Physics," Vol. 1, p. 421. 
Ross, J. F. S., " Introduction to the Principles of Mechanics," Cape, 1923. 
Haussmann, K., "Der Kreiselkompass in Dienste des Bergbau," 1914. 



206 DEEP BOREHOLE SURVEYS AND PROBLEMS 

about which it spins unaltered in direction whether rotating 
or not. If spinning it resists any attempt to alter the direc- 
tion of its axis, and the gyroscopic torque dominates when 
the gyroscope is given a very high speed as is common in 
borehole practice. This precession is so important in 
borehole gyrocompasses that it appears to merit fuller 
detail. 

At the beginning of this century several trials were made 
to establish a gyrocompass. Doctor Anschiitz-Kaempfe 
succeeded in bringing out a gyroscopic compass which 
maintained its direction for a long time — 24 hr. — in the 
laboratory. He however recognized that it was extra- 
ordinarily difficult, perhaps impossible, to create a gyro- 
scope complete and perfect in equilibrium; he therefore, 
in 1906, added to the gyroscope with three degrees of 
freedom one with two degrees of freedom and in this way 
arrived, by progressive simplification, at his first gyroscopic 
compass with only one high-speed wheel and with damped 
oscillations. In the most recent form of the Anschiitz 
compass for nautical purposes there are three similar wheels 
which compensate the regular oscillations of the ship. 

Precession. — When a simple wheel disc rotates and no 
lateral force or torque is exerted upon it, it persists in its 
position because every particle of mass in the disc endeavors 
to remain in the plane set up. This inertia grows with the 
mass of the disc and with the angular velocity of the rota- 
tion. If a torque is exerted on the quiescent disc (which 
can be imagined as an upward pull on one axis end or a 
downward pressure on the other end) the plane will incline 
laterally. 

If a torque or lateral pressure be now appUed to the disc 
when rotating, we have the inertia of the disc on the one 
hand and the inclination of the tilt on the other, so that it is 
a question of what will be the result in the motion due to 
these two factors acting simultaneously. Let us consider 
Haussmann's^ simple presentation of these important 
facts, which we have slightly modified for our purpose. 

1 Ibid., p. 51. 



GYROSCOPIC COMPASS METHODS OF SURVEYING 207 

Figure 144 shows a plan and elevation of a rotating disc 
I with a force acting partially on its axis; also its imagined 
neighboring position II into which the disc is for the time 
being inclined. (For clarity the drawing is much exag- 
gerated.) In the plan the narrow ellipse I gives the original 
position and II the inclined position of the disc. The direc- 
tion of the disc in plane I in the plan is shown by the hori- 
zontal diameter AB oi the ellipse. Any mass particle m 
of the rotating disc I will remain in this position in conse- 
quence of its inertia, even if the disc inclines a little due 





Elevoi+ion 



Plan 



Fig. 144. — Precession. 



to a lateral torque. This direction of persistence must 
thus also be present when the particle m rotates in the 
inclined plane II. If the particle is now compelled to 
rotate in plane II it still has the tendency to remain in the 
direction of plane I. The tangents to plane II give the new, 
those to I the old, directions of movement. These direc- 
tions are only equal in C and D, also in E and F; in all other 
points they differ. Let the divergence of corresponding 
tangents be indicated by 5 and the angle between planes I 
and II by A and further let the angular rotation of the 
particle proceeding from D be co, then we get the relation 



sm H = sm ^ sm co 



(12) 



208 DEEP BOREHOLE SURVEYS AND PROBLEMS 

For small angles 5 = A sin w. The value of 8 is nil in points 
D and F, a maximum in A and a minimum in B. 

Corresponding to the divergence of the tangents there 
appears a force acting at right angles to the disc, which is 
nil in D and grows to A and from here on again declines to 
nil at F then back to D in the same manner but taking a 
course in the contrary direction. 

These lateral components effect a rotation of the spinning 
disc about the diameter DF or in relation to the original 
position I about the normal diameter CE; and this turning 
annuls at every moment the tendency to lateral inclina- 
tion. This turning motion at right angles to the direc- 
tion of the applied force is called precession. We shall 
not go into the lesser motion appearing in the periodic 
repeated dip and rise of the axis known as nutation. The 
preceding construction applies very fully to a gyroscope 
imagined as frictionless. In practice the axis of the 
gyroscopic disc will, in the course of time, show more and 
more marked inclination owing to the action of friction. 

As a proof that a force applied to the axis of a rotating 
gyroscope brings about a lateral movement we have but to 
consider the common spinning top or child's hoop. 

The Action of the Gyroscopic Compass. — Imagine a 
gyroscope wheel suspended at the equator so that its axis 
A^,Ae (Fig. 145) is horizontal and it goes round from west 
to east. Regarded from west or south the wheel has a 
clockwise direction of rotation as shown by I in (Fig. 145). 
Next instant the wheel, owing to the earth's rotation, is in 
position II (much exaggerated in the drawing). 

Owing to the inertia of the disc the axis AJAJ stays in 
position II parallel to its former position A^Ae, while the 
direction line of gravity in II makes an angle of coq ^ 15^ 
with that in I, owing to the interval t in time between 
positions I and II and the fact that gravitation acts toward 
the earth's center. Thus the disc axis is no longer at right 
angles to the direction of gravity; its east end is too high, 
so that the force of gravity acts unequally on the axis. 
On the west end an upward pull is exerted and on the east 



GYROSCOPIC COMPASS METHODS OF SURVEYING 209 

end a down pull acts. The force of gravity thus gives 
rise to the precession motion of the gyroscope whereby 
the east extremity of the axis moves toward the north. 
When the axis comes into the plane of the meridian the 
effect of gravitation on both ends of the axis is similar and 
balances. The gyroscope remains in this position because 
the meridians at the equator run parallel, and thus it is 
independent of the earth's rotation. The meridian is 
the position of equilibrium which the gyroscope tends to 
attain in consequence of the earth's rotation. On the equa- 
tor the turning axes of the earth and the gyroscope are 




parallel and their rotational senses are the same. In 
general all rotating bodies tend so to place themselves 
that in similar turning senses their turning axes are similarly 
directed. If now we hang the rotating wheel not on the 
equator but on any other chosen spot on the earth's surface 
the gyroscope will still tend to set its axis in the same direc- 
tion as that of the earth. This can not occur completely 
owing to the line of gravitation being here no longer normal 
to the earth's axis as at the equator, but being inclined 
to it. The gyroscope will now, as far as is possible, set its 
axis in the line of the earth's axis, and it attains its greatest 
proximity to this when its axis lies in the meridian. If 
at any place of latitude </> the axis of the gyroscope makes 



210 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



an angle <t) with the earth's axis, this is then the smallest 
of all possible angles between a horizontal line and the 
earth's axis. For a horizontal line of any azimuth Awe 
get the corresponding angle of inclination a, from Napier's 
laws. Thus 

cos a = cos </) cos A (13) 

Angle a is greater than 4> because its cosine is smaller. 
In Fig. 146 point I^ rotates, owing to the earth's rotation 
in time t, to position 11^. The gravity direction lines in 




I^ and 11^ do not now make an angle of coo = I5t as at 
the equator, but a smaller angle co^ which can be computed 
from 



sin 



. Wo 
sm -^ cos cj) 



(14) 



Thus for small intervals of time we may write 15t cos 0. 
The directing force of the gyroscope thus decreases with 
latitude, it being only a half in 60 deg., a quarter in 75 
deg., and a tenth at 85 deg. latitude, of the force at the 
equator. It is nil at the pole where all great circles are 
meridians. On the gyroscope axis swinging into the merid- 
ian plane from the east, the east end of the axis is somewhat 



GYROSCOPIC COMPASS METHODS OF SURVEYING 211 



too high and the gyroscope oscillates over the meridian 
out again. As the north axis then dips below the horizon 
a back oscillation sets in. To decrease these oscillations 
sufficiently rapidly a damping device is provided with 
the gyrocompass. In Anschiitz's method the suspension 
of the compass is obtained by having it connected to a 
body which floats in quicksilver. Then at any azimuth 
of the gyrocompass the buoyancy of the mercury takes up 
the gravitational force, acting through the earth's rotation 
on the one extremity of the axis, in the form of a pull 
upward, and that on the other end is compensated as a 
pull downward by its proper weight. 

The Kiel Nautical Instrument Company's Gyroscopic 
Compass for Borehole Surveys. — This apparatus^ was 
formerly introduced for warships and 
submarines by the firm Anschiitz of 
Kiel. Indeed, it alone made long- 
distance underwater navigation 
possible. 

It is let into the hole on a cable and 
2-m. measurements are taken with it. 
It is held centrally by guide brushes to 
maintain always the same vertical in 
the hole. A measuring box (Fig. 147) 
has two pendulums arranged to rotate 
about the axis of the apparatus; they 
swing in two planes at right angles to 
one another and a small gyrocompass 
adjusts the measuring case so that one 
pendulum swings in the east-west and 
the other in the north-south direction 
regardless of how the apparatus turns 
on being let down. Figure 148 is a 
schematic view of the measuring box 
with an east-west pendulum which hangs vertical while the 
box is inclined with the hole. (The dip here is exaggerated 

1 Martienssen, 0., Eledrotechnische Ztschr., Heft 24, p. 462, 1920; p. 
694, 1919; and pp. 862, 887, 1911. 




Fig. 147. Fig. 148. 



212 DEEP BOREHOLE SURVEYS AND PROBLEMS 

being seldom more than 1 deg.) Below the point of the 
pendulum is the midhne m, m, of the apparatus, and, 
owing to the dip, the pendulum deviates a little way a 
from this line east or west. This amount a is measured 
and if, say, the deviation is a mm. and the pendulum 20 
cm. long, then in a length of 2 m. the hole is displaced 2 cm. 
to the west. If we carry all measurements at 2 m. and add 
all the deflections a we get the total deviation of the hole 
toward the west in centimeters. Similarly the north-south 
pendulum point may give deflections h at the same times 
and these are also added as above algebraically. Both 
displacements are plotted on coordinate paper which 
permits the position of the hole with respect to its origin 
being easily found. Thus, for example, for a 300-m. depth 
in a hole, we employ 150 measurements on the north-south 
and east-west pendulums and add them for the resulting 
displacement, say west and south. 

Figure 1 (Plate XIII) shows the interior of the apparatus 
which is protected by a steel casing, for loosening which a 
nut at the bottom can be drawn out. It is tightened with 
India-rubber gaskets which will suit pressures of 150 atm. 

The most important part of the device is the gyrocompass 
hanging under the inclination measurer, the action of which 
is based on Foucault's law that the earth exerts, on every 
horizontal rotating shaft, by its revolution, a force which 
turns the shaft in the north-south direction, so that the 
turning of the earth is of the same sense as that of the shaft. 

The directing force we have discussed on page 208 to 
be the product of the moment of inertia of the wheel, its 
angular velocity, the angular velocity of the earth, the 
cosine of the geographical latitude and the sine of the angle 
between the meridian and the wheel axis.^ 

If the suspension is free enough this directing force lets 
the axis of the wheel swing into the north-south line, for 
then the sine of the angle is nil, but in order to attain suffi- 
cient force the velocity of the wheel must be great. 

1 Martienssen, O., Die Theorie des Kreiselkompasses, Ztschr. f. 
Instrumentenkunde, 1913. 



GYROSCOPIC COMPASS METHODS OF SURVEYING 213 

The gyroscopic compass constructed to meet these 
demands is shown in Fig. 2 (Plate XIII) and set in the 
lowest part of the apparatus (Fig. 1). A ring-shaped vessel 
a filled with mercury is fixed on the rotatable measuring 
case in a housing with the aid of bows b. A ring-shaped 
float c in the mercury vessel holds the wheel cap e by a neck 
d. In this cap or case runs the gyrowheel on ball bearings, 
the wheel itself being of nickel steel and having a short- 
circuit rotor pressed on it. The stator of the small alter- 
nating-current motor which drives the wheel is fixed in the 
wheel case, and it is supplied with a 400-cycle per second 
current, by means of fine silver wiring, causing the wheel 
to make 25,000 r.p.m. 

The construction of such a quick running alternating- 
current motor with short-circuit armature is extremely 
skillful; the high number of revolutions demands much 
copper in the rotor so that the turning moment be small, 
otherwise the wheel will not exceed a definite speed range. 

The wheel hangs in its case as deep as possible below 
the float compatible with the tube width against which it 
would bump if very deep. In this position gravitation 
tends to hold the axis horizontal and the axis adjusts itself 
to the meridian by Foucault's principle, stated above, 
because the entire floating system is arranged rotatable 
about the center rod /. A directing force of some tenths 
gram-centimeter suffices to turn this small gyrocompass 
but not the whole measuring box, so for that reason the 
following arrangement is adopted. On the floating system 
is fixed a contact bead g which, when the float with the wheel 
turns right or left, makes contact with a contact spring 
on right or left and in this way a so-called ''turning, 
take-up, or compensating motor" changes its rotational 
sense. This is to be found in the uppermost part of the 
inclination measurer (Fig. 3). It is a small direct-current 
motor with double armature winding and commutators 
on both sides; and by the contact bead one or the other 
of the windings is cut out causing the armature to rotate 
in the opposite way. 



214 DEEP BOREHOLE SURVEYS AND PROBLEMS 

This take-up motor turns the measuring box with the 
mercury vessel and contact springs to the rotations of the 
gyrocompass, for the bead is only out of contact when it 
hangs free between the contact springs on the mercury 
vessel. Consequently, the measuring box is always in a 
definite position with respect to the gyrocompass and 
thus also to the meridian. In Fig. 2 (Plate XIII) the lower 
bearing of the compass box is shown at I and in Fig. 3 L 
is the upper bearing of it. The box itself is shown in Fig. 4. 

The east-west pendulum a swings in the picture plane 
and the north-south pendulum h at right angles to this. 
Under each pendulum is a registering casket kk with a 
registering strip running close under the points. Over 
the pendulum points lie the cores or armatures dd of two 
small electromagnets as broad as the strips. When taking 
measurements the current is sent into the electromagnet 
by a telegraph key on the surface; the core strikes the 
pendulum and presses a fine needle on the end of the pendu- 
lum into the registering paper thus perforating it. Break- 
ing the circuit the electromagnet operates a catchwork 
driving the registering strip 5 mm. forward ready for the 
next measurement. 

On opening the apparatus at bank and taking the strips 
out from the casket and reading the deflection of the several 
holes from the midline of the paper, two separate tables are 
entered up with the data from the two strips. The sum 
of the entries in the two tables, east-west and north-south, 
gives the displacement at the depth concerned. 

Figure 1 shows the head of the apparatus; the various 
leads of the cable are tightened with India-rubber the 
winding cable itself being of medium steel and held by bolts 
h. Eight lines encased in gutta-percha and jute yarn 
take the current to the wheel, take-up motor and electro- 
magnets. The rope is also covered with gutta-percha to 
distribute the load at the bearing guide roll. 

The cable drum and motor are in a special lorry as also 
are the current source and transformer for the direct- 
current portion and also the necessary controls for the gyro- 



GYROSCOPIC COMPASS METHODS OF SURVEYING 215 




[[ 



2 



-'ygf"4M 



in. 




Fig. 2.— The 
gyrocompass. 



jPj(j, 1. — Fig. 3. — The dip Fig. 4. — Registra- 
Complete measurer. tion section, 

instrument. 

Plate XIII. — The Kiel Nautical Instrument Co.'s gyroscopic compass borehole 

apparatus. 




216 BEEP BOREHOLE SURVEYS AND PROBLEMS 

wheel current, the take-up motor current, keys, etc. The 
method has been frequently applied in measuring the devia- 
tion of freezing shaft boreholes. The makers 
claim the remarkable accuracy of about 1 in 2,000. 
Anschiitz Borehole Deviation Instrument. — 
Doctor Anschiitz^ employs the gyroscopic compass 
for fixing the direction of deviation and a rigid 
plumb bob for the amount of deviation. He 
equips both with transmitting apparatus and 
combines these with a receiving apparatus on the 
surface so that one can read there at once the 
position of the plumbing apparatus at any chosen 
position in the borehole. The plumbing device is 
let into the hole with a cable from which the depth 
is read. 

Since the results are given directly on the merid- 
ian, the astronomical north and the direction of 
gravity the apparatus is free from partial measure- 
ment errors. Each individual observation is com- 
pletely independent of the others, thus obviating 
the transference of errors. The superiority of this 
method will thus be greater at greater depths. 
Since an opening of the tube throughout the appli- 
cation is not necessary, the dip measurer is always 
ready for use and yields unvarying data. Figures 
149 to 152 show the constructional parts of the 
inclination measurer. They are made up of the 
transmitter (Figs. 149-151) and the indicator or 
receiver aboveground (Fig. 152). 

The Transmitter: Plumbing Cylinder and Chief 
Parts. — This is shown in Fig. 149 as a pressure- 
Fro 149 W^^^ ^t^^l cylinder a bearing a gyrocompass b 
The trans- giving the direction, and a rigid plumb c with 
^^ ^^' Cardan suspension for giving the amount of incli- 
nation of a borehole at any position. This cylinder has 
steel feeler brushes d above and below and is let into the 

1 Haussmann, K., Gluckauf, July 4, p. 1076, 1914, also Bergassessor 
WiMMELMANN, Kohle UTid Erz, Nos. 13-15, pp. 323-379, 1924. 



GYROSCOPIC COMPASS METHODS OF SURVEYING 217 



borehole by the cable e. Compass and plumb are both 
provided with a transmitter, which are connected by elec- 
tric conductors in the interior of the holding cable to the 
receiver aboveground. The two principal parts of the 
plumbing cylinder are the gyrocompass and 
the hanging plumb bob. 

The Gyrocompass. — Under the steel cover 
there is a lead to the compass (Fig. 150). 
The capped compass case a carries a three- 
phase motor with a short-circuit rotor. 
This consists of iron sheets with aluminum 
rods and star plates. Over the axis a two- 
pole alternating-current winding is slid. 

At an alternating current of 0.25 amp. and 
120 volts, 500 periods, the body wheel of 
the compass is made to rotate about its 
horizontal axis at 30,000 r.p.m. The wheel 
is closed about by a cap which hangs on a 
floating ball bearing. The ball floats in a 
vessel of mercury b (Fig. 150). On the float 
body a small contact ball c is sprung. This 
rotates with the wheel independent of the 
mercury bath and the tube. Contact paths 
d are fixed on the mercury bath and they 
have slits. These turn independent of the 
wheel with the bath and lamp e in the casing 
jacket. The mercury bath has a Cardan sus- 
pension, i.e., gimbals, in the lamp e and is connected to the 
transmitter motor g by means of a spur wheel drive/ through 
a shaft. This motor g rotates the bath and lamp as long as 
the contact bead slides on one of the contact paths d. As 
soon as the bead has reached the slit the electrical circuit is 
interrupted and the turning ceases. Then the transmitter 
motor has reached its previously known normal position 
compared with the wheel. The motor of the transmitter is 
connected electrically to the receiver motor, the graduated 
scale of which turns back. Here one may read off the 
position of the transmitter motor respecting the compass 



Fig. 150.— 
Anschiltz appa- 
ratus. The 
gyrocompass. 



218 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



wheel and therewith respecting the meridian (by providing 
a meridian Hne or azimuth Une through the borehole). 
Thus we get the lateral angle aboveground. The damping 
of the circle is easily obtained by chambers between which 
some oil runs in and out on the oscillations of 
the wheel axis. 

Above in the steel shell comes the plumbing 
device (Fig. 151). The rigid plumb bob a 
hangs by Cardan suspension in a guide and is 
prolonged in a rod b as far above as it hangs 
below. The plummet carries above and below 
a small contact bead or ball. Each of these 
two balls runs in a slit between contact tracts 
c and d on a lateral support capable of tipping 
e and /. In space the slits stand at right 
angles to one another. The upper support turns 
about an axis which is in a position at right 
angles to that of the lower one. The inclina- 
tion is resolved into two components at right 
angles to one another. Naturally the same 
action can be obtained as well by two sepa- 
rate pendulums. When the contact balls fit 
laterally into their slits the current is cut off and 
the parts concerned will be so far displaced 
laterally that no further side contact can take 
place until the rigid plummet hangs free. The 
contact chariot of the transmitter is, however, 
connected to the corresponding parts of the 
receiver by means of the electrical conductor in the cable. 
As long as the transmitter parts are in lateral motion 
the current to the receiver is cut off and it there displaces a 
motor contact carriage in the same manner. Both compo- 
nents are compounded in the receiver yielding the total 
motion of a magnet bar whose deviation from a mean 
position is shown on the concentric rings of a graduated 
plate by means of a small iron ball on a rod which moves 
according to the magnitude of the inclination of the bore- 



FiG. 151.— 
Anschiitz ap- 
paratus. The 
plumbing de- 
vice. 



GYROSCOPIC COMPASS METHODS OF SURVEYING 219 

hole. Amount and direction of inclination are read off 
the receiver in tenths of a degree. 

The Receiver. — The mode of action of the receiver (Fig. 
152) has already been described. The alternating motor a 
in the receiver runs synchronously with the motor in the 
gyrowheel chamber in the plumbing apparatus and turns 
the counter 6 (detached in the figure) back in the direction 
for reading the inclination. Another motor c displaces a 




Fig. 152. — Anschiltz apparatus. The surface receiver. 

main carriage d on a horizontal spindle on which a second 
carriage e turns, also horizontal, but can be displaced 
90 deg. to the main carriage. On the carriage e sits a 
bar magnet / with an end pointed upward 90 deg. which 
reaches close under the scale plate b and on it pulls a small 
iron ball. By this ball, on concentric circles, the magnitude 
of the inclination is read. Doctor Anschiitz has investi- 
gated the possibility of a coupling table on which the course 
of the borehole is automatically indicated on the plumbing 
apparatus being let into the hole. With such a device one 
would only have to draw in the depth indicated by the cable 
on the line of course of the borehole. 

The Transport Lorry. — A lorry carries the cable on a drum 
as well as a switch plant and all accessories. The cable is 
marked in 2.5 to 25 m. for reading depths. It carries 
inside it the conductor cable from transmitter to receiver. 



220 DEEP BOREHOLE SURVEYS AND PROBLEMS 

The apparatus suffices for plumbings up to 700 m. and can, 
with corresponding cable lengths, be used for any depth. 

Test Plumbings. — Tests with the above dip measurer 
in a pipe in a shaft of the Deutscher Kaiser works were 
carried out to a depth of 350 m. and have yielded the same 
results on insertion and extraction and on repetition. 
These have been checked by surveys and give agreeable 
results as far as comes into general practice. Since in this 
method partially active errors are avoided, which would 
make repetition results false, the conclusions to be drawn 
from the tests are that for a well thoughtout, ingenious and 
rapid working apparatus it is quite accurate and satisfies 
all the demands of practice. It should still be mentioned 
that the dip measurer is also applicable as a stratameter 
for cores. Speaking of this instrument, after observing a 
test, Prof. Haussmann of Aix says,^ ''The mathematical 
and physical basis on which the appliance is constructed 
permits us to recognize that it is free from inherent errors; 
thus must it also yield correct results with increasing 
depths." This accuracy fulfills the preliminary conditions 
for the success of freezing shafts, i.e., by proving the course 
of the boreholes. 

Surwel Gyroscopic Clinograph. — This remarkable device 
marks the most recent practice in the adaptation of the 
gyroscopic principle to the survey of borehole deflection. 
The principal features of the well-known Sperry^ gyroscope 
of navigation are applied. 

This apparatus consists of three main parts: (1) the box 
level gage (Fig. 2, Plate XIV) ^ for ascertaining the vertical 
inclination, which is placed uppermost of the three in the 
apparatus ; (2) the film camera (Fig. 3) making simultaneous 
moving-reel records above and below ; and (3) the lowermost 

1 Haussmann, K., Mitt. Markscheiderwesen, p. 60, Sonderdruck, 1914. 

2 Glazebrook, Sir R., "Dictionary of Applied Physics," Vol. 1, p. 421; 
Vol. 4, p. 255; also British Patent No. 15,669/15; Rawlings, A. L., "The 
Theory of the Gyroscopic Compass," p. 18, Macmillan & Co., Ltd., 1929. 

3 By the courtesy of the Sperry-Sun Well Surveying Company, Phila- 
delphia. 



GYROSCOPIC COMPASS METHODS OF SURVEYING 221 



-Wire Line 



■Wire Line 
Socket 



Ball Bearing 
/ Swivel 



Shock 
Absorber 

Jiminq 
Device 

Box Level 
6age 

Insfrumen+ 
■•''Rrofecfing 
Casing 

Film Camera 

■Gyroscope 

Shock 
"Absorber 

Gasket 

■Batteries 

■BaHery 
Profecfive 
Casing 



Shock 
'Absorber 



Fig. 1. 




Fig. 2. — The box 
level gage. 




Fig. 4. 




Fig. 3. — The camera. 



Fig. 5. — The pointer compass. 




Fig. 6. — Specimen photo strip from borehole. 
Plate XIV. — The Sperry-Sun Well Surveying Co.'s gyroscopic compass device. 



222 DEEP BOREHOLE SURVEYS AND PROBLEMS 

unit, the gyroscope itself (Fig. 4). These three units are 
assembled, screwed tight, in a high steel jacket 5^ in. 
external diameter, the apparatus itself being about 43-^ in. 
in diameter. The lower joints carry dry batteries operating 
the gyroscope and illuminating the film camera. The top 
joint ends in a ball-bearing swivel which enables the appara- 
tus to be sent into the hole either on the drill stem or on a 
wire line. It is thus independent of many of the objection- 
able torsional features which render the results of so many 
devices unacceptable for accuracy. This latter feature 
plus the north orientating tendency of the gyroscope (and 
here the special restraining appliances) make this class of 
instrument independent of the effects due to twist on 
insertion and extraction of the apparatus. It is claimed 
that the casing of steel will withstand the mud pressures 
encountered in holes down to 10,000 ft. deep. The gyro- 
scope, maintaining the features of rigidity and precession 
discussed mathematically at the beginning of this chapter, 
offers great revsistance to any attempt to alter the direction 
of its axis by being caused to spin, by means of the electric 
motor self-contained, at a very high speed, as in the case 
of Anschiitz model and that of the Kiel Nautical Instru- 
ment Company previously described. The direct-trans- 
mitting motor rotates the gyroscopic disc at about 10,000 
r.p.m., and this latter is specially balanced to maintain 
its axis in the geographical meridian^ when once set there. 
A pointer coinciding with and controlled by the gyroscope 
(Fig. 5) is set above the gyroscope on its axis over a grad- 
uated arc. To this latter is attached a non-magnetic 
watch with large minute and second hands giving readings 
to }i sec. This enables computations of depth to be made 
for each site recorded in the hole. A thermometer may 
also be added here for reading the temperatures encountered 
which yields data not only on direct thermal conditions 
but for computation corrections if desired. 



1 See Rawlings, op. cit., p. 124, for mathematical discussion on balancing 
the disc. 



GYROSCOPIC COMPASS METHODS OF SURVEYING 223 

The camera^ (Fig. 3) which is of special design employs 
a 16-nim. perforated motion-picture film and has a capacity 
of 50 ft. There are two lenses recording pictures simultane- 
ously in opposite directions, up and down. One lens 
photographs the compass scale and gyroscopic pointer 
below with the watch and thermometer (if any), while 
the other photographs the position of the bubble in the 
graduated level gage box above. These lenses have to be 
very accurately aligned on the same optical axis and focus, 
thus superimposing two pictures on one film as shown in 
Fig. 6, Plate XIV. This enables one to read off the amount 
and direction of deflection at the same time, while the time 
for the depth computation is given as well. The film 
take-up is worked through gears by a small electric motor, 
which also operates a synchronized and adjustable contact 
device providing the necessary light flashes for taking the 
pictures. The camera motor is controlled by an accurate 
timing device guaranteed to vary less than 7 sec. per day. 
Thus the camera has a capacity for taking up to 1,000 
photographs, giving a practically continuous record of the 
hole. It also records going into, and coming out of, the 
hole. 

The hox level gage (Fig. 2) is a ring with top and bottom 
of ground special glass, the former disc being spherical and 
having concentric graduations. The position of the bubble 
relative to these graduations gives the amount of vertical 
inclination as in the depthometer of a previous chapter. 
Three different levels are provided with each instrument 
having maximum inclinations of 20, 40 and 55 deg., 
respectively. This range of registration of dip angle far 
transcends that of any other device employing the gyro- 
static principle. Preliminary runs with an acid-bottle 
apparatus decide which of these box level gages to select 
for a particular case. To ensure rapid response of the 
bubble to quickly altering inclinations the nature and 
size of the bubble are specially allowed for in the material 

1 We are indebted here for some notes kindly supplied by the makers, 
The Sperry-Sun Well Surveying Company, Philadelphia, 



224 DEEP BOREHOLE SURVEYS AND PROBLEMS 

of the fluid. Lag and oscillation of the bubble have also 
to be provided against while temperature effects are com- 
pensated by expansion coils. 

For operation with a wire line a line meter is applied 
to the derrick reel starting from zero, and a watch syn- 
chronized with the gyroscope watch is used for making 
time readings every 25 or 50 ft., according to the depth 
of the hole. Thus the depths are easily obtained. The 
apparatus is run at a fairly constant speed of 150 to 180 ft. 
per minute in cased holes, thus taking about 1 hr. for a 
5,000 ft. hole, but this speed does not apply equally to open 
holes. A closed traverse is got by taking readings running 
into and out of the hole and this provides the check survey. 

The whole apparatus is entirely automatic and the obser- 
vations are taken at predetermined intervals of time. 
Regardless of tilt or case spin, these records yield the direc- 
tion and inclination of the north pointer of the gyroscope 
and its amount from the bubble. The stability of the 
gyroscope and the sharp responsiveness of the bubble 
permit of this even at the above rapid lowering speeds. 
These and the times are recorded all together, as seen in 
Fig. 6, during the continuous running of the apparatus 
and herein will be noted the great time saving over previous 
types of apparatus described. 

After dissembling the clinograph at bank the film is 
removed and developed, as in Fig. 6, whence we get the 
dip, orientation and time or depth. Applying now correc- 
tion factors for cardinal errors, parallax and refraction 
(which are established for each instrument) the survey is 
plotted in one vertical section and two horizontal ones, 
respectively, north-south and east-west and a model 
constructed if needed. 

The makers claim for their apparatus independence of 
magnetic and torsional influences, great saving of time, 
easy manipulation and interpretation of records, rapid 
mapping, great accuracy and simplicity in handling either 
on drill stem or a line, large dip range and automatic 
action. 



CHAPTER X 

GEOPHYSICAL METHODS OF INVESTIGATING 
BOREHOLES 

Introductory Note. — Geophysical methods of locating 
mineral fields and particular ore bodies and minerals 
are already well established and can be divided into six 
main groups, viz., gravitational, electrical, magnetic, seismic, 
thermal, and radioactive methods. Of these, so far, only 
electrical and seismic or elastic methods have been applied 
to coring and borehole problems. 

By a geophysical method we mean one in which some 
established physical property of matter, i.e., ore body, 
oil, coal, etc., is investigated, excited or otherwise examined 
in contrast with its surroundings and the features betrayed 
measured at a distance. At present bodies at depths down 
to about 600 ft. have been successfully located by these 
means. In many cases only one particular method can be 
applied, e.g., seismic methods (artificial ground shocks) 
alone suit the geological features connected with the deep 
oil zones of Iraq, while in Sweden electrical methods are 
most favored. We have detailed these methods elsewhere,^ 
so will not enlarge upon them here. 

Electrical Methods.— The transmission and distribution 
of electrical energy currents of various kinds which are sent 
out from artificial or natural sources form the basis of the 
most widely adopted methods of scientifically investigating 
the earth's crust. There are four chief divisions: 

1. Methods in which a current is purposely generated 
and introduced into the ground. 

2. Methods in which the currents generated in bodies 
themselves in the ground are harnessed. 

^ Colliery Guardian, May to September, 1927, and Haddock, M. H.^ 
"Location of Mineral Fields," Chap. VI, Crosby, Lockwood & Sons, London. 

225 



226 DEEP BOREHOLE SURVEYS AND PROBLEMS 

3. Combinations of 1 and 2. 

4. Electrical waves. 

Broadly speaking for our purpose electrical methods 
can be grouped into two main groups, i.e., potential and 
electromagnetic. A brief sketch is essential to a compre- 
hension of the method of electrical borehole investigation 
due to the brothers Schlumberger, the only electrical 
method which has been employed for this purpose. 




Fig. 153. — Normal course of electric current lines between two electrodes in a 
homogeneous underground. 



Potential Method. — If an electric potential of +e volts be 
applied to a point a, while at another point b the voltage 
is zero, then between the two field electrodes, a and b, a 
pressure (potential) difference or electromotive force e 
prevails, which produces a current i, that flows from a to 6 
in imaginary current lines, the pressure decreasing all the 
time from +e at a to nil at b. The planes or sections which 
show equal potential difference toward the electrode a or 6 
can be connected by planes of equal pressure called equi- 
potential planes or level planes. From the potential 
theory we learn that such equipotential planes stand every- 



GEOPHYSICAL METHODS OF INVESTIGATING 



227 



where at right angles to the current Hnes, so that if the 
spacial distribution of the current Hnes is determined in any 
manner the equipotential planes are also located. These 
current lines have the construction of an ellipsoid of many 
shells, Fig. 153 being a hemispherical section for the current 




Fig. 154. — Horizontal section through the equipotential lines. 

lines between two electrodes in a homogeneous under- 
ground. In many cases the ore body itself also generates 
a polarization current in its surroundings. The distribu- 
tion of the current in a body depends upon the form and 




Fig. 155.- — Right section through the equipotential lines. {After Schhimberger.) 

spacial arrangement of the conductivity in the body and 
on the position of the field electrodes. Simple regular 
bodies are amenable to direct mathematical estimation, 
as in the well-known school example, while approximate 
rules are applied to the complicated cases of nature; 
deformation of the equipotential curves is sought (Figs. 
154, 155) after observing the potential at a sufficient num- 
ber of plotted places on or under the earth's surface. 



228 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



SuflEicient has been said to indicate that the electric or 
electromagnetic field set up by the current directed to 
the underground is investigated on the assumptions (1) 
that the earth is a good conductor, (2) that the conductivity 
of the object sought differs sufficiently from that of its 
surroundings, and (3) that the object sought lies in such a 
way in the current region that the deflection caused in the 




Fig. 156. — Schematic example of spontaneous polarization according to Schlum- 

berger. 



electric field or electromagnetic field can be detected on the 
surface. Schlumberger says^ "the equipotential curves of 
small radius belong to small spherical surfaces which lie at 
small depths in the earth and are therefore unaffected by 
deep-lying masses. The deep-seated masses thus only 
influence curves of large radius." 

Schlumberger' s is distinct from any other method, 
where the whole measuring processes are continually fed 
by an electric current. It is executed by cutting out the 
direct-current carrying electrodes and the measurement is 
made on the surface by the polarization of the potential 
distribution brought about in an ore body. If a constant 
direct current flows through a mineral deposit, Schlum- 
berger has ascertained that an electrolysis takes place in 
the ground on the surface of the deposit (Fig. 156) if water 

1 "Etude sur la prospection electrique du sous-sol," 1922. 



GEOPHYSICAL METHODS OF INVESTIGATING 229 

is present. Then the ore deposit will become polarized^ 
and transformed into a secondary element, which discharges 
itself according to the interruption of the polarizing current. 
While the period of discharge arises if there is a measurable 
potential difference on the surface, he has succeeded with 
the help of polarization phenomena in distinguishing 
between minerals of metallic conductivity, such as mag- 
netite, pyrites, lead glance, etc., and groundwater strata. 
Now the application of direct current also brings a polariza- 
tion of the searching probes wherein the ground plays 
the part of an electrolyte, so that in potential line surveys 
special electrodes or non-polarizable electrodes^ made of zinc 
plates in concentrated zinc sulphate solution and other 
chemical types are used. Alternating current of average 
frequency is now often applied in order to avoid this 
polarization phenomenon at the probes, and the course of 
the current in such cases no longer depends only on the 
ohmic resistance of the separate rock layers but also on the 
capacitative and inductive alternating-current resistance, 
which also brings about phase displacement and fluctuations 
in the current, thus causing variations in the form of the 
potential lines. However, this latter aspect does not affect 
electric coring methods, so that we will content ourselves 
with referring the interested reader elsewhere.^ 

Schlumberger's Method of Investigating Boreholes. — 
The application of the above method has been extended 
by the brothers Conrad and Marcel Schlumberger of Paris 
to investigations on lithological data, dip of strata, faulting, 
intercalations and other features accounting for the devia- 
tion of boreholes. They consider the electrical conductivity 
of the constituents of the earth's crust which fluctuate very 
widely; that of the badly conducting overwhelming majority 
of the constituent minerals depending in a very decisive 

^ Schlumberger, C, Ph^nomene ^lectrique produit par les gisements 
metalliques, Compt. rend., p. 477, 1922. 

^ Bartjs, C, U. S. Geol. Survey Mon., No. 3, pp. 309 et seq. 

^ Ambronn, R.., "Methods of Applied Geophysics," pp. 131 et seq.; 
Heine, H., Die Einflusse von Induktion und Kapazitat bei geophysikaUschen 
Potential-liniemessungen, Ztschr. Phys., p. 219, 1926. 



230 DEEP BOREHOLE SURVEYS AND PROBLEMS 

manner not only on the ground but also on its moisture 
content and the substances dissolved in this moisture. (We 
shall not submit a table of conductivities and resistivities 
here because they vary tremendously for the different strata 
of the earth's crust even in the same rocks. They should 
be determined experimentally for every place being investi- 
gated.) With the exception of certain metallic ores which 
have the property of electronic conductivity (like metals), 
rocks are capable of transmitting an electric current only 
by means of the water which they have imbibed.^ Therefore 
their conductivity is solely electrolytic, and disappears 
entirely with drying. The solid mineral elements are 
almost perfect insulators, which the current skirts in 
following the damp veins. The following approximate 
laws have been deduced therefrom: 
The specific resistivity of a rock is 

1. Inversely proportional to the quantity of imbibed 
water contained in a cubic meter of rock. 

2. Proportional to the resistivity of this water, therefore 
roughly inversely proportional to the total quantities of 
salts dissolved per unit volume of the water. 

Thus the resistivity of a rock is in inverse proportion 
to the total weight of electrolytes dissolved in a cubic meter 
of the rock. Schlumberger says that these underlying 
principles are, of course, subject to many modifications, 
according to conditions; the angle at which sedimentary 
strata are inclined, for instance, affects the resistance; a 
rise in temperature reduces the resistance, etc. 

By the accompanying illustration (Fig. 157) we see the 
measuring apparatus in diagrammatic form. It comprises 
three insulated cables 1, 2, and 3, suspended in the hole 
4, and terminating toward the bottom in three electrodes 
A, M and N immersed in the well water 5. The radii, 
AM equals r and AN equals r' , are chosen greater than the 
diameter of the hole. The electrode A serves to send 
the current into the soil and the electrodes M and N to 
measure the difference of potential produced by ohmic 

1 BiGNELL, L. G. E., Electric Coring, Oil Gas Jour., p. 33, Feb. 6, 1930. 



GEOPHYSICAL METHODS OF INVESTIGATING 



231 



effect between these two points by the passage of current 
into the soil. 

To send forth a current by the electrode A the latter is 
connected, by means of the insulated cable 1, to one of the 
poles of a source of electricity E situated aboveground, 
the other pole of the latter being earthed at any point B 
close to the well. To measure the difference of potential 
resulting between M and A^, these two electrodes are con- 



% 



'^y/^^^^,' 



%. 









J 



N 

"5 "J 



V 



Fig. 157. — Electric coring. 



nected by means of the insulated cables 2 and 3 to the two 
terminals of a potentiometer placed aboveground. 

Knowing the distances r and r', the intensity i of the cur- 
rent force (measured, for example, by an ammeter) and the 
difference of potential A 7 between M and iV (measured 
by the potentiometer), it is possible to calculate the average 
resistance of the soil surrounding the measuring field AWN, 
if the soil is uniform, in the following manner : 

The current i flowing from A into the soil creates, by 
ohmic effect, a group of equipotential surfaces enveloping 
A. These surfaces are, by reason of symmetry, practically 
spheres centered in A , always excepting : 



232 DEEP BOREHOLE SURVEYS AND PROBLEMS 

1. The region quite close to A, where the presence of the 
borehole full of water and the dimensions of the electrode 
A cause a certain disturbance. 

2. The region away from A where the equipotential 
surfaces are affected by the earthing at B or the non- 
homogeneity of the soil (metal casing of the hole, etc.). 

In particular, the two equipotential surfaces S and S' 
passing through the points M and N are spheres of known 
dimensions by reason of r and r\ These spheres intersect 
the column of water without noteworthy distortion. The 
measurement of potential between the electrodes M and N 
immersed in the water is, therefore, equivalent to a measure- 
ment made in the interior of the soil at the same distances 
r and r' from the electrode A. 

The application of Ohm's law between the spheres S 
and S' leads to the formula: 

i2 = 47r ^ • ~— (15) 

I r — r 

which gives the required resistance, since aV, r and r' are 
known. ^ When the soil in the vicinity of the measuring 
field AMN cannot be regarded as homogeneous in structure 
the computations become more involved but nevertheless 
furnish results that are sufficiently correct for practical 
purposes. 

An advantage of this type of equipment is its portabihty 
and the speed with which a well can be surveyed or logged, 
the entire equipment weighing less than 3,000 lb. The sur- 
veying can be done at the rate of 3,000 ft. per hour when the 
machine is in position.^ A chart is made on special 
paper wound on synchronized drums for lowering the cable 
with electrodes and taking the record. As these electrodes 
are withdrawn to the surface, readings are made at chosen 
intervals of 5 to 40 ft., dependent on local conditions 
and desire for information. The uncased part of the hole 

1 Lancaster-Jones, E., The Earth Resistivity Method of Electrical 
Prospecting, Mining Mag., June and July, 1930. 

2 BiGNELL, op. cit. 



GEOPHYSICAL METHODS OF INVESTIGATING 233 

only is investigated because the high metalUc conductivity 
of the casing prevents electrical resistivity readings in the 
lined parts of the hole. Given ample geological data, 
lithological sequences can be established fairly accurately 
by this method. This has been done in Europe and South 
America, while in Oklahoma and Kansas electrical key 
horizons have been fixed by it. By slightly altering the 
technique the dip of the strata can be got in favorable cases, 
i.e., by noting the point of surface emergence of an electric 
current sent into a relatively conductive stratum. Since 
oil and gas offer high resistance to the flow of current, the 
conductivity of which we have seen depends on the amount 
of water present, we may be able to trace oil wells with the 
basal salt water and the other wells in the oil proper. 
Discontinued cores can also be completed by an electrical 
log so as to determine all the beds traversed and get 
their thicknesses. 

The cost increases as the log length (uncased part of the 
hole) increases, and the method is useful where no cores 
are yielded, as in churn drilling. Electrical key horizons 
will make up for any lack of geological ones, thus permitting 
of more precise correlation. It also enables us to get the 
data of faulting, since these markedly affect the con- 
ductivity range. Enough has been said to show that this 
infant method is pretty vigorous and appears to have a 
hopeful future. 

Seismic Methods. — This method of investigating the 
earth's substructural conditions has been adopted for 
places where the overburden wholly or partially hides the 
solid geological structure of the region. It depends on the 
propagation of waves in the earth, the passage of which 
are affected by the physical characteristics of the rocks 
traversed; they are therefore subject to the laws of the 
elastic theory. Consequently the velocity of an elastic 
wave is determined by the modulus of elasticity of the rocks, 
the density, and Poisson's transverse contraction coefficient 
for the various media. Elastic waves in air or water are 
known as sound waves and those in the solid mass of the 



234 DEEP BOREHOLE SURVEYS AND PROBLEMS 

earth as seismic waves. In air and water only longitudinal 
condensation and rarefaction waves are formed, and in 
these every particle oscillates to and fro about its position 
of rest in a direction parallel to the direction of propagation. 
In air the velocity of propagation v, under a pressure p, 
density p, and specific heat ratio x at constant tempera- 
ture and constant pressure, is v equals Vxp/p, while in 
liquids it is v equals Vk/p, where k is the compressibility. 
But in solids the relations are very complicated, and, 
indeed, not yet fully comprehended but are determined, 
as said, with the aid of Poisson's constant o-, which is the 
ratio of the extension of a pulled bar to its accompanying 
decrease in cross-section being between 0.2 and 0.5 for the 
different solid substances; and also with Lame's coefficients 
X and jjL, particularly the latter, which indicates the stiffness 
or rigidity modulus and is therefore of great practical 
significance. These must be known from laboratory tests, 
because the speed of the waves varies so greatly with differ- 
ent media; for instance, soft friable rocks, like sand, propa- 
gate earthquake shock waves at about 400 m. per second, 
while hard primitive rock shows a velocity of about 
4,000 m. per second; in general, from 1 to 4 km. per second, 
and these figures, of course, vary with the differing densities 
and elasticities of the different media traversed. Doctor 
Mintrop^ has undertaken observations collecting and 
developing usable methods of investigation through the firm 
Seismos, Ltd., in Hanover. 

All workers in this field are indebted to the pioneering 
work of Wiechert^ and his able pupil, Gutenberg,- the result 
of whose labors, combined with the very extensive experi- 
mental material of many earthquake observatories, have 
brought about practical conclusions upon which modern 

^ MiNTROP, L., "tjber kiinstliche Erdbeben," Intrn. Kong. Diisseldorf, 
1910. Abtlg. IV, Vortrag No. 14, Seismos-Gesellschaft. Mttlgn. d. I. "Erfor- 
schung von Gebirgsschichtcn und nutzbaren Lagerstatten nach dem seis- 
michen Verfahren," Hanover, 1922 (the Seismos Company's own 
publication). 

2 Repts., Imp. Soc. Sci., p. 195, Gottingen, Berlin, 1899; also Sieberg, 
A., "Applied Earthquakes, Geological-Physical," p. 283, Jena. 



GEOPHYSICAL METHODS OF INVESTIGATING 235 

methods of location by means of time-travel curves or 
course-time curves depend. They also depend very much 
on the relation of the load to the deformation, i.e., Young's 
modulus E. The relations of E and a- on the one hand and 
Lame's coefEcients X and ^ on the other are as follows:^ 

_ a _1 E ^ 1 1 

^ ~ (1 +0(2 - (r)'^'^ 2*l + (r''' 2*X + m' 

E = --^{?>\ + 2,) (16) 

and when disturbances in the interior set up the usual 
longitudinal waves with velocity V and transverse waves 
with vibration velocity V of the particles at right angles 
to the direction of propagation, we have^ 

T/ - / ^ + 2m _ \E 1-0- y, ^ jl, 

^ ~^~~P Vp (1+0(1 -2a)' Vp' 

= iMzm (17) 

Vp 2(1+0 ^ '^ 

Only two equations are presented for determining these 
most important quantities, E, a and p, or X, fx and p, so that 
with reliable results a third relation can be found, otherwise 
suitably complete assumptions must be made. Compara- 
tively little is known of the vagaries of earth wave motion, 
especially in the case of artificial earthquakes which are 
liberated for seismic ground research and borehole surveys. 
It will be seen that the direct study is very closely allied to 
seismology as applied to actual earthquakes, but the study 
of the behavior of purposely produced ground concussions, 
as by the explosion of dynamite, gives rise to many features 
which are not recorded of natural or long-distance earth- 
quakes, such as surface air and sound waves, certain 
types of strata limit reflection, etc. 

1 ZoEPPRiTZ, K., Repts., Imp. Soc. Sci., p. 66, 1919, and p. 121, 1912, 
Gottingen ; also Davison, C, " Manual of Seismology," Cambridge University 
Press. 

* Ambronn, op. cit., p. 152; also Haddock, M. H., Colliery Guardian, p. 
333, 1927. 



236 DEEP BOREHOLE SURVEYS AND PROBLEMS 

When speaking of natural quakes it should be noted 
that about 3,000 km. is considered an average distance 
(epicentral) earthquake. Now the study of these waves, 
their accompanying waves and features, the resultant 
reflected waves from different boundaries in the earth, 
and above all the course-times of all these, depends on 
individual rock characteristics; hence we may by their 
aid learn certain rock structures and borehole deviations 
in the earth which could not otherwise be revealed. The 
chief regions of application are those in which we wish to 
obtain the thickness of overburden resting on older beds. 
This has been successfully carried out in the preliminary 
work of some Swedish electrical surveys.^ 

Moreover, the seeking of dislocations, the determination 
of deeper strata directions and therewith also saddles and 
basins and borehole data are located by this means. These 
waves make themselves felt at their points of emergence 
at the earth's surface in slight impulses and movements, 
the waves themselves being in the nature of harmonic 
vibratory motions, which, in the case of uniform and 
homogeneous rocks, are shown in a correspondingly 
uniform and harmonic, and indeed characteristic, motion 
of the transmitted waves. But since the crust of the earth 
is decidedly heterogeneous not only in chemical constitu- 
tion but in physical formation and deformation, the waves 
are hampered in transit and their vibratory properties 
defaced in a manner which often is quite bewildering, 
but the changes are always proportional to the changes 
in the material traversed. The consequent alteration 
in the velocity, frequency, and amplitude of the motion, 
and the arrival time factors at reception stations have then 
to be investigated as they occur. On the waves striking 
the limits between strata of different elasticities, etc., 
broken waves are set up in the second medium and at the 
same time a part of the wave energy is reflected, and, 
indeed, according to the kind of wave being discussed, 
i.e., longitudinal or transversal, corresponding condensa- 

^ SuNDBERG, K., "Electrical Prospecting in Sweden," p. 31. 



GEOPHYSICAL METHODS OF INVESTIGATING 237 

tional and distortional waves appear, making the conditions 
of motion very complicated and often indecipherable.^ 
In addition, other kinds of waves appear which are con- 
nected only with the surface, the most important being 
the Rayleigh waves^ which are due to the combined 
action of the longitudinal and transverse waves at the 
bounding surfaces and their state of vibration. They 
displace along the earth's surface with the velocity V equals 
0.9 F' approximately. The waves transverse to the Ray- 
leigh waves are called Love's waves. ^ They vibrate 
particles at right angles to the direction of the propagation 
in the upper strata.* These oscillating movements are 
determined with their components by various means, such 
as pendulum weights suitably suspended or set. The rela- 
tive movement of the pendulum mass^ about its support 
axis illustrates, usually after magnification by lever 
systems, the relative ground movement. 

Those instruments with optical recording devices are 
preferable, owing to the freedom from friction of contact 
surfaces found in other types and the facility for magnifica- 
tion. The curves show not only the relative movement 
of the ground, support, and pendulum mass, but also the 
wave frequencies and time factors of main and subsidiary 
waves. Figure 158a shows a typical seismogram or record 
of an average distance natural earthquake wherein only the 
surface or ground types are indicated. It is now extremely 
important to distinguish between the several kinds of waves 
set up previous to discussing the record. When a quake is 

1 Repts. Imp. Soc. Sci., p. 66, Gottingen, Berlin, 1919. 

^Proc. Math. Soc. {London), No. 17, p. 4; Phil. Trans. Roy. Soc. (London), 
No. 203, p. 1, 1904. 

^"Textbook of Electricity 1907: Some Problems of Geodynamics," 
Cambridge, 1912. 

* For the strict theory see Mainka, C, "Physik der Erdbebenwellen," 
Berlin, 1923; Davison, C, "Manual of Seismology"; Ballore, Montesstjs 
DE, "La geologic seismologique," pp. 453-458; Amer. Seis. Soc. Bull., Vol. 
2, p. 127, 1912; Adams, F., and E. G., Cooker, Carnegie Inst. Pub., No. 46, 
Washington, 1906. 

^ See Keilhack, K., "Lehrbuch der Prak. Geol.," Vol. 2, Chap. I, for some 
complete information with figures. 



238 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



caused purposely, as by explosive charges, air and sound 
waves are set up and these are not surface earth waves. 
Air sound waves are distinctly indicated on the record for 
quakes due to human agency, and they are quite distinct 
from those movements and tremors of the earth due to 
earth waves. These are propagated much more slowly 




I 2 3 4 5 6 16 
Fig. 158a. — Impulse record. 



I 
^ V 



^S 



Speed of Recording Paper =One Inch Per Second of Time 

■Impulse record 

Fig. 158b.— {After Kithil.) 
Fig. 158. 



than deep earth waves; consequently, although they are 
generated at the same time, they appear later on the record 
as will be seen in Fig. 1586. Figure 159 (after Rankine) 
shows a gelatine shot artificial shock record. 

The new and only British seismograph instrument of the 
Cambridge Instrument Company is an advance upon 
Mintrop's original apparatus being more sensitive and 
dependable. It has been evolved as a result of the Iraq 
oil-field researches of Dr. A. 0. Rankine, Professor of Phys- 
ics, at the Imperial College of Science and Technology.^ 
Its advantages over other types lies in the linking device 

1 We are indebted to Dr. Rankine for Fig. 160 and the details. Sympo- 
sium at the Institution of Mining and Metallurgy, Apr. 18, 1929; see also 
British Patent Specification No. 17402/29. 



GEOPHYSICAL METHODS OF INVESTIGATING 239 

for obtaining greater magnification for smaller earth 
movements. It comprises a highly sensitive instrument 




Explosion of 1 Lb. Gelignite, Distance 1200 Yards 



Time Vio+h. Second 



F i I . I '. I . \' ^^^ \, 




Explosion of 11/2 Lbs. Gelignite. Distance 1200 Ycirds Time Vioth. Second 

Fig. 159. — Seismographic records. 

for measuring vertical vibrations (the vibrometer) and, 
a camera for recording them. The vibrometer, shown in 




Fig. 160. — ^^Seismograph. 



Fig. 160 with the outer cover removed, consists of a heavy 
mass H fixed on a short lever carried on flexible steel 
hinges at /. This weight is balanced by springs Oi and O2. 



240 DEEP BOREHOLE SURVEYS AND PROBLEMS 

Oi is the mainspring and O2 is a fine adjustment spring 
controlled by the screw F. The lever carrying the mass H 
is extended by the light cone N. For transit the clamping 
screw G is released and the weight H is withdrawn from the 
tubular fitting into which it is normally fitted. The system 
is then automatically clamped, owing to the load on the 
spring Oi. At the end of the cone iV is a fine rod J, the other 
end of which bears lightly on a horizontal disc in such a 
way that any small movement of the mass H relative to the 
base of the instrument causes a rotation of the disc. 
A mirror is so mounted that this rotation causes a corre- 
sponding movement of the mirror which is recorded photo- 
graphically by a compact form of paper camera. The 
moving mirror system, which is the only delicate part of 
the apparatus, forms a complete unit which can be easily 
removed and replaced, and which is disconnected from the 
rod J by a simple automatic device. Light from a lamp 
mounted in the camera passes through a convex lens K and 
is reflected from the mirror so that an image of a slit in front 
of the lamp is focused down to a bright spot of light on the 
photographic paper. 

Malamphy^s Seismic Method of Surveying Boreholes. — 
For localizing the work of a seismograph, i.e., concentrating 
it upon a given spot, a form of wave detector of electric 
line microphone or geophone may be sunk to any desired 
depth in a borehole. This has been done by M. C. Malam- 
phy in the western American oil fields^ and has yielded 
hopeful results. 

The geophone is lowered into the hole to the desired spot 
and shots (gelignite or dynamite) are located about the 
hole with seismographs at known distances from the hole, 
for time records. The method is much simplified and it is 
thought that errors are distributed uniformly by this 
method. If the hole is straight the time for each shot will 
be proportionate to the distance of each less the strata 
corrections, etc., for the place being considered. If the hole 

1 Seismic Method of Determining Deviation in Drill Holes, Oil Weekly. 
p. 32, Apr. 26, 1929. 



GEOPHYSICAL METHODS OF INVESTIGATING 



241 



is crooked the time will vary accordingly. The time taken 
by the wave in traveling to the geophone will give the length 
of its path when we know the vertical velocity of the local 
formations by the above or similar computations (Mr. 
Malamphy simplifies these computations drastically), since 




Fig. 161. — (a) Plan sketch showing ideal location of shot points for deter- 
mining deviation of hole from vertical. H' indicates the position on the surface 
directly above the point at which the detector is placed in the hole. This point 
is determined by arcs from the various shot points. (6) Vertical section along 
line E W showing crooked drill hole and path of the seismic waves to the detector, 
(c) Vertical section showing method of shooting profile to determine true depth 
and average vertical velocity. {After M. C. Malamphy.) 

the depth of the apparatus in the hole is known direct 
(Fig. 161). The time taken by the shot wave from W 
will be less than that from E (Fig. 161&) if the hole is 
crooked. Knowing the depth and vertical path we may 
get the other side of the triangle and thus the distance 
from H' to E and to W; the point H' being on the surface 



242 DEEP BOREHOLE SURVEYS AND PROBLEMS 

directly above the spot in the hole where the detector is 
placed. Since we know the distance between E and W 
and the position of D, the hole mouth, we can thus get the 
apparent deviation of the hole along line EW. Now choose 
any other pair of shot holes say on line A^^S and get the bore- 
hole deviation along it similarly. 

From this it will be seen that we have first to obtain this 
average vertical velocity of the seismic wave. The above 
authority proceeds as follows : The known depth of the geo- 
phone being he, and S the distance of the shot from the bore- 
hole mouth, then the length of the seismic path I from 
explosion to detector is 

P = he' + S'~ (18) 

and if t^, ts, ts and tw be the seismic times from shot points 
N, S, E and W, and F„ the approximate value of the average 
vertical velocity, we get a first approximation of 

K = ^ t I' t ^ 1 !^ (18«) 

In 'T ts ~r ^E ~r tw 

Is, Ie, etc., being the lengths of the seismic paths from the 
corresponding points S, E, etc. We then get the approxi- 
mate position H' of the geophone in the hole thus 

In = VatN] Is ^Vats, CtC. (186) 

If the distance of the surface points directly over the 
detector from each shot point be S'n, S'w, etc., we get 

S'n = ■\lT7'~^h?; S's = ^ls'-K\ etc. (18c) 

Drawing arcs from the several shot points as centers 
and using S' as radii, their intersections will give the point 
H' on the surface directly above the detector acceptably 
enough for practical purposes. A refinement of the method 
is proposed by the inventor^ and this of course greatly 
enhances the accuracy of the method. 

This extra refinement, particularly in measuring the 
seismic times t and the surface distances S, is very important 

1 Oj). ciL, p. 70. 



GEOPHYSICAL METHODS OF INVESTIGATING 243 

and should if possible be deduced by (18c) above, because 
the average vertical velocity encountered will in some cases 
vary from 5,000 ft. per second for shallow depths up to 
12,000 ft. per second for greater depths. An error of 
1/1,000 sec. in the seismic time here will show an error of 
5 to 12 ft. in the length of the seismic path. Hence the time 
record should read direct to 1/1,000 sec. and at very least 
1/100 sec. 

The charge of explosives should be planted at about 
10 ft. down to prevent it blowing out, and greater accuracy 
will be had if we take h, U . . . etc., the seismic paths 
from shots Si, S2 . . . etc., and their times ti to . . . etc., 
for getting the true depth h and the true average vertical 
velocity V thus 

l,-^ = h^ -^ Si'- . . . etc. 
hence 

a general equation for all points. Plotting this in the lineal 
form ax -\- y -\- C = with values of x as functions of y 
{t^ as functions of S^) we get the straight-line graph with 
the slope a = V^ and^ the ordinate intercept C — h^ in the 
usual way and so by normal coordinate geometry for 
gradients and interpolated values. The charges in the hole 
seldom exceed a few pounds, though in major geophysical 
work, as in the deep lying anticlines of the Persian oil 
areas, over a hundred pounds have been employed in one 
shot, the depth feature being in the region of 4,000 ft. in 
places. 2 

The method adds decided advantages in an extensive 
field in that it provides data as to subsurface conditions 
simultaneously with the above. One of these advantages 
is the structural image we get of the underground from a 
study of the curves when plotted as above. This will be 
best appreciated by an example or two. 

1 Ibid., p. 70. 

2 Professor Rankine, lecture before Loughborough Scientific Society, 1929. 



244 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



We may consider this accessory information yielded by 
this method in the same way as Professor Heiland of the 
Colorado School of Mines. In Fig. 162 we have a hard 
limestone overlain by loose sandy clays, the former having 
a wave velocity of ?^ and the latter of Vi when a charge is 
fired at S. The shock wave intervals are measured off on 
the graph, shown where the scales E 
of the concussion are set off at inter- 
vals of 200 and 280 m.; the corre- 
sponding times are the ordinates. 

At El and Eo the course-time and 
wave velocities are proportionate 
(straight-line law), the shock being in 




Distance 






Fig. 162. 



Fig. 163.— Diagrams of 
time-travel curves over 
different tectonic features. 



one uniform stratum with velocity Vi, but from the latter point 
onward the waves lengthen, running in the deeper stratum 
with the higher wave velocity V2. The resulting course- 
time curve shows a nick at k, such nicks always betraying 
density, etc., changes in the strata. The position of the 
nick point gives the surface limit ^ of the hard stratum at 

^ "Electrical Prospecting in Sweden," p. 31. 



GEOPHYSICAL METHODS OF INVESTIGATING 245 

right angles to the overburden of thickness h. Here 
Vi equals 1,000 m. per second, V2 equals 5,000 m. per second, 
and h equals 200 as will be seen at once. 

The relations for inclined beds are theoretically shown in 
Figs. 163a to d.^ Sufficient has been said to show the possi- 
bilities of this method.^ 

This method only requires about 2 hr. for planting, and 
survey points and measurements need only be taken every 
300 to 600 ft. down the hole. 

The advantages of the method are : 

1. It determines the location at each depth independent 
of other positions. 

2. It gives the horizontal and vertical location of any 
spot desired in the hole. 

3. It will determine the bottom of the borehole without 
the necessity of having to survey the entire hole. 

The disadvantages are mostly those due to its recent 
adoption, lack of experience and inexpert manipulation 
of the apparatus and computations. 

^ Heiland, C, Ztschr.f. Instrm., p. 417, Berlin, 1925, or Eng. Min. Jour.- 
Press, Vol. 121, No. 2, p. 54, 1926. 

2 Shaw, H., Mining Mag., p. 201, April, 1930. 



CHAPTER XI 



PROBLEMS 



In this chapter we purpose deahng with those problems 
useful in prospecting and location work generally as are 
provided by a study of the data afforded by borehole devia- 
tion instruments, core evidences and photographs of bore- 
hole walls. 



A. ONE-BOREHOLE PROBLEMS 

To Obtain the Penetration Point of a Borehole and a 
Stratum. — Of the several mathematical methods of dealing 




Fig. 164. — Borehole dipping with the beds. 

with this problem few are suited to meet the needs of bore- 
hole conditions, because the data usually assumed are 
frequently the least accessible. The best method for our 
purpose is the conditional formula method. Let the bore- 
hole BBi (Fig. 164, here shown dipping with the stratum 
but steeper than the beds) have a dip a and the stratum 
8. It meets the stratum at C at a height h above a horizon- 
tal plane laid through any point A in the stratum, e.g., 
a point known in a mine, on an outcrop or located otherwise. 
Point A need not be accessible if we know the dip of the 
stratum 8. If B' is the vertical projection of B, the bore- 

246 



PROBLEMS 247 

hole mouth, on the said horizontal plane we can get the 
positions of it and point C, where the hole hits the stratum, 
from the condition h + gradient height of BC = H, the 
total height of B above the said plane = height coordinate 
of B less that of A = B^ — A^, where z is the space (height) 
coordinate subscript above any given datum like sea level. 
Let the horizontal distance from 5 to C be x and the 
gradient of BC will be a function of x. The distance 
between C', the vertical projection of C on the plane, and 
the strike line through A is ^iC", then 

xt&ii a -\- AiC t&n 8 = H (19) 

and AiC may be obtained from the right-angled triangle 
AiC'A2, which is right angled at Ai, thus: 

AiC = C'A2 sin di = {B'Ao - x) sin di 

where di is the angle between the borehole andstratumstrikes. 

Again, from triangle AB'A-i we get B'Ai = AB' —. — — 

sm uif 

where d^ is the angle between the line from the known point 
A to the horizontal projection of B at B' . That is to say 
02 is always known from the survey notes. Therefore 



A,C' = (aB' ^-^ - :^ sin d^ = AB' sin d 
\ sm di } 



2 — X sm Q\ 



Substituting in Eq. (19) above we get 

X tan a + {AB' sin Q2 — x sin 0i) tan 6 = H 
Whence 

H — AB' sin 62 tan 5 

X ^^^ ; 

tan a — sin di tan 5 



(20) 



and all the quantities on the right hand side are known so 
getting X, we may easily fix the space coordinates of C by 
first obtaining h. The signs of the various terms in this 
expression vary according to the position of the given 
magnitudes in space, thus: 



248 DEEP BOREHOLE SURVEYS AND PROBLEMS 

a. H is positive if point B lies higher than A. 
h. AB' sin 62 tan 5 is positive if point B lies on the dip 
side of the strike line through A. 

c. Tan a is always positive, and the sign of the second 
term in the denominator is arranged thus: sin ^i tan 8 must 
be additive when the direction senses of the stratum and 
borehole are different, i.e., opposed, and subtractive when 
the other case arises, i.e., when they dip together. 

d. While X is positive the penetration point C lies on 
the dip side of the borehole from B, i.e., it is negative for a 
rise borehole. 

I. Boreholes at Right Angles to the Strike of the Strata 
a. VERTICAL boreholes: lengths 

The customary way of expressing the borehole lengths 
will be seen from Fig. 164 to be 

T 

L = BC = 



cos a 

and considering this in connection with Eq. (20) we get 

^ X H — AB' sin 62 tan 5 , , 

L = BL — = —. -. — -7—7 ^^ (21) 

cos a sm a — Sin 01 tan 8 cos a 

In a vertical borehole, its dip being 90 deg., the above 
becomes 

L = BC = H - AB' sin 62 tan 8 (21a) 

Several cases arise in practice, and these are easily grasped 
from a study of surface boreholes such as oil wells, thus: 

1. The Borehole Is on the Upstream Side of the Outcrop 
and the Stratum Dips toward It (Fig. 165). — If h be con- 
sidered as the compound term following the sign in Eq. (21a) 
we note in this case that 

L = H + h 
or 

L = H + AB' sin 62 tan 5 (216) 

Note. — The angle 62 is in the plane of the reader's vision in Fig. 165 
and it can assume any number of values according as AB' changes in 
bearing; that is to say, according as the borehole mouth is displaced 
laterally from the known point of outcrop A. 



PROBLEMS 



249 



2. The Borehole Is on the Upstream Side of the Outcrop 
but the Stratum Dips Away from It (Fig. 166). — Here we 
get 

L ^ H -h 

or 

L = H - AB' sin d^ tan 5 (21c) 

NoTE.^In this case h must be less than H. 




l_ J^'vl 

B' '■h = -AB'5ine2+nn(5 
Fig. 166. 




h=+;SBsin92+an(S 



Ji .^ 



Fig. 167. 

3. The Borehole Is on the Downstream Side of the Out- 
crop and the Strata Dip toward It (Fig. 167). — Here we 
get 

L = h- H 
or 

L = AB' sin d^ tan 5 - F (21d) 



250 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



Note. — In this case H must be less than h and if the strata dip in the 
other direction no location is possible. 

These will cover all cases of vertical boreholes. 

b. INCLINED boreholes: lengths, displacements and depths 

In these cases the boreholes may have an infinite number 
of dips in amount in two directions at 180 deg. from one 
another, i.e., corresponding opposed and 'together" 
dips, and still be at right angles to the strike of the stratum, 
provided the hole does not leave the plane normal to the 
stratum strike, i.e., its full dip or rise direction plane (Figs. 
168, 169). The angle 02 of Eq. (20) is 90 deg., making it 

H ± AB' tan 5 



X = 



tan a + tan 8 



according to the relations of the dips of borehole and 
stratum. It will be found more convenient to measure 
the surface slope 7 in these cases. 




C_-i-^ 



Fig. 168. 



1. The Borehole and Stratum Dip in the Same Direction 
with the Borehole Upstream of the Outcrop (Fig. 168). 

la. The Length of the Borehole, 

TT 

BB" = —^ 

sm a 



PROBLEMS 251 

B"B' = Hcota 

B"E = B"C sin (a - 8) 

^, ^ B^E^ ^ AB" sin 5 

sin (a — b) sin (a — 6) 

AB" = if (cot 7 + cot a) 

rr A T>f/ 

BC = BB" + B"C = L = -^^ + 



sm a cot 5 sm a — cos 



a 



i = // (^ + ''"t ?- + ""*" ) (23) 

\Sin a cot 5 sin a — COS a/ ^ ' 

If the borehole is downstream of the outcrop the first 
term in the bracket is negative; on a level surface B. van- 
ishes, also 7, and since then AB" = AB' = AB, the above 
form is not applicable, a modification of either Eqs. (216), 
(21c) or (21c^) being then most suitable, which will yield 
the length, thus 

BC = L = 4^^^ (24) 

sm {8 — a) ^ ^ 

and so on for other dimensions which need not be repeated 
here. 

16. The Displacement of the Borehole.— This is the shift 
of the hole and will be in the full dip direction here (Fig. 
168). 

Displacement = DC = B'B" + FC. 

= H cot ex + B"C cos a 

= n cot a + 77 :r~r. tt 

(tan a cot 5 — 1) 

DC^H (cot a + ;«tT+COta \ 

\ tan a cot 5 — 1/ ^ ^ 

Wherein the first term on the right is negative if the bore- 
hole is downstream of the outcrop; and if the surface is 
level 

DC = BC cos a (26) 



252 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



Ic. The Total Depth of the Borehole. — This is the distance 
to the base, i.e., BD. 



BD = H + h 



= H + 



B"E sin a 

sin (a — 5) 



and since 



we get 



B"E = AB" sin 5 



= H + 



AB" 



BD = H[\ + 



cot 5 — cot a 

cot 7 + cot a 



cot 5 — cot 



(27) 



2. The Borehole and Stratum Dip in Opposite Directions 
against One Another with the Borehole Upstream of the 
Outcrop (Fig. 169). 



^r 




Fig. 169. 



2a. The Length of the Borehole. 
BB" = H/sin a 
B'B' = H cot a 



and 



AB" = H (cot 7 - cot a). 
L = BC = BB" + B"C 



B"C = 



PROBLEMS 253 

B"E AB" sin 5 



sin (180 - b - a) sin (5 + a) 



L = J^+ AB" 



sin a cot 8 sin a + cos a 
L = h(J-+ ;f ?--">*. ) (28) 

\Sin a cot 5 Sm a + COS Q!/ •^ 

Compare with Eq. (23) above where similar remarks 
apply respecting the altitudes of the derrick floor and the 
outcrop. 

When the surface is flat AB" = AB' = AB and then 

i = BC = ^^HLL (29) 

sm (5 + a) 

Compare with Eq. (24) above. 

26. The Displacement of the Borehole. 
DC = B'B" + FC 

AB" 



H cot a + 



tan a cot 5 + 1 



2c. The Total Depth of the Borehole. 
BD = H + h 

BD = H+ ,/5 , =h(i + '''1]-'''1^ ) (31) 

cot 5 + cot a \ cot 5 + cot a/ ^ ^ 

The reason for choosing the persistent term AB" is 
because it is the dimension most likely to give the least 
trouble in obtaining in practice. 

C. HORIZONTAL BOREHOLES 

Here the inclination of the borehole is nil, so that in 
Eq. (20) a = deg., making the expression for the displace- 
ment X (Fig. 170). 

H — AB' sin 02 tan 8 AB' sin 9-, — H cot 5 ,„^, 

^ ^ . = . (32; 

— sin di tan 8 sin di ^ ^ 



254 DEEP BOREHOLE SURVEYS AND PROBLEMS 

d. THE SHORTEST BOREHOLE FROM A GIVEN POINT TO A STRATUM 

These are not strictly normal to the strata but are best 
dealt with here. 
We have already shown in Eq. (21) that this length is got 

by 

^ H ±AB' tan a sin e. 

sin a + tan 8 sm di cos a ^ ' 

the signs depending on the relative dipping senses of the 
stratum and borehole. 

If we consider the point B of the borehole mouth fixed, 
then the length of the hole is a function of a and ^i, its dip 




'ir|iiiiji || ii| || |TiiirnT 



_™^ 



Fig. 170. — Horizontal borehole. 

and bearing; it is thus dependent on two variables. The 
number of connections is thus infinite. 

e. THE SHORTEST POSSIBLE CONNECTION, AT A GIVEN BEARING, 
BY A BOREHOLE TO A STRATUM 

We might get, with the aid of the calculus, the values of 
a and 02 to meet this case, but the same result is obtained 
by stereometry, wherein we note that the line falling at 
right angles to the stratum dip line is the shortest in the 
said direction. That is to say, the hole hitting the stratum 
face ''square on" (not perpendicular) is the shortest at a 
given bearing. Thus the dip of this hole will then be 90 — 5 
and its bearing that given. 

The shortest of all possible boreholes will be in the plane 
at right angles to the strata dip, and its dip will be 90 — 6, 



PROBLEMS 



255 



its bearing that of the seam dip plus 180 deg., say ,8 + 180 
deg., where jS is the direction of full dip of the stratum and 5 
its amount. 

Substituting in Eq. (21) we get for the shortest connection 
at a bearing 62 between hole and stratum strike directions 

5C = i7 cos 5 + AB' cosec 5 sin di (34) 

/. THE SHORTEST OF ALL POSSIBLE BOREHOLES TO THE STRATUM 

Here the vertical plane holding point A in the stratum 
and B on the borehole 
mouth must have the 
direction ^ + 180 deg., 
so that 62 = 90 deg., 
and we get (Fig. 171) 




BC = H cos b + 

AB' cosec 5 (35) 

This is similar to E'E 
of Figs. 168 and 169 

„!„„ Fig. 171. — Borehole dipping against the beds. 

We shall not deal with upward holes, since these do not 
come under deep boring ; also we will not go into the variant 
forms of Eqs. (21a), (216), (21c) and {2ld) above, which arise 
with contrary senses of hole and strata dips. Varying 
these, as we have done in the cases of vertical and inclined 
normal holes, will give the reader no difficulty and preserve 
the space at our disposal. 

II. Boreholes Not at Right Angles to the Strike of the 

Strata 

All the cases are covered by Eq. (21) for length, i.e., 
H ± AB' tan 8 sin 62 



L = BC = 



sin a + sin d\ tan 6 cos a 



(36) 



and it appears needless to draw the upstream and down- 
stream cases, since the previous examples are particular 
cases of these problems. The related displacement and 
depth problems will need no further embellishment here 
either. 



256 DEEP BOREHOLE SURVEYS AND PROBLEMS 

The succeeding problems on boreholes not at right angles 
to the strata strike appear to provide sufficient variant 
forms of the above. Since in these cases we are dealing 
with cores actually at the stratum or seam being sought, 
our notation will have to be modified a little. 

INCLINED SINGLE BOREHOLES: METHODS OF OBTAINING DIP, 
THICKNESS AND DIRECTION OF BEDS 

Vertical boreholes will always yield direct data for the 
dip of the beds especially if they provide cores. Then the 
dip is the maximum inclination shown by the bedding; 
therefore we shall not deal with them but consider inclined 
or meaned deviated boreholes. 

1. To Obtain the True Dip of Beds from a Borehole 
Not at Right Angles to the Strike of the Bedding.^ — Here 
four possible cases of borehole penetration arise in practice, 
and each of these takes two forms according as the hole is 
a dipper or a riser, as in Figs. 172 and 173 and Plate XV, as 
follows : 

Case 1. — Where the beds dip or rise in the same direction 
as the hole, but more steeply (Figs. 172, 173). 

Case 2. — Where the beds dip or rise in the same direction 
as the hole, but less steeply, Case 2, Plate XV. 

Case 3. — Where the beds dip or rise in the opposite 
direction to the hole and more steeply than a plane normal 
to the plane through the drill hole and the strike of the beds. 
Case 3, Plate XV. 

Case 4. — Where the beds dip or rise in the opposite direc- 
tion to the hole and less steeply than a plane normal to 
the plane through the drill hole and the strike of the beds. 
Case 4, Plate XV. 

The general formula is most easily derived for the case 
of a hole dipping in the same direction as the beds (Figs. 172, 
173). 



1 White, E. E., Eng. Min. Jour.-Press, Vol. 98, No. 12, p. 524, or "Loca- 
tion of Mineral Fields," p. 98, Crosby, Lockwood & Sons. 



PROBLEMS 



257 



Let 



i = the inclination of the drill hole XX i from the 

horizontal. 
di = the angle between the bedding and the axis of the 

hole which is obtained from an examination of the 

drill cores. 
d = the difference in strike of the bedding and the drill 

hole. 
8 — the true dip of the strata. 




Fig. 172. 



Let 




Fig. 173. 

A = any point on the drill hole — in our figures it is 
the point at which the drill hole enters the bed 
or seam — from which a perpendicular can be 
erected on to the plane of the bedding. Call 
this perpendicular Ab. 



258 DEEP BOREHOLE SURVEYS AND PROBLEMS 

Ad = another perpendicular dropped from A on to the 
horizontal plane which passes through the inter- 
section of the drill hole with the plane of the 
bedding. 

abc = the above bedding or seam plane having a right 
angle at c. 

adc = the above horizontal plane through the inter- 
section of the drill hole and bedding plane. 
cAh and cAd represent vertical planes at right angles to 
ac, the strike of the bedding, and drawn through 
A. 

Aa = the length of the seam or bed pierced as given 
by the core. It will be found convenient in all 
cases to express this as unity. 

The line Ac makes an angle ^ with the horizontal plane, 
and an angle a with the plane of the bedding. (The words 
"bedding" and ''seam" have similar meanings in the 
following discussion.) These angles are Acd and Acb, 
respectively, and, as in Case 1, their sum is equal to the full 
dip. Then 

cos i = ad 
cos 5i = ab 

sin i = Ad 
sin 8i = Ab 

ac ac 

cos d = — 5 = : 

ad cos I 

.'.ac = cos i cos 6 
and 



be = V{ab)^ — {ac)'' = Vcos- 5i — cos^ i cos^ 



Ac = V{bc)' + {Ab)^ = Vcos- 5i — cos^ i cos^ d + sin^ 5i 



= VT — cos- i cos- 6 

. , . 1 Ab sin 5] 

Angle sm-^ -r— — 



Ac Vl — cos^ i cos^ 6 



Angle sin-^ 



PROBLEMS 
Ad sin i 



259 



^c Vl - cos2 i cos^ d 

Referring to figures: 

Case 1. — Here it will be seen by Figs. 172 and 173 that 

b ^ a + ^ 

therefore 

5 = sin 5i 4- sin i /gyx 

Vl — cos^ i cos^ B 

Case 2. — Here the full dip is obtained by 5 = /3 — a 
(Case 2, Plate XV) 



DIPPERS 




Case 2. <f- ff-oc 




Cose 3. <f=l8Q°-[i-oc 




Cass 4: <f=oc-p 

Plate XV. — One- 



RISERS 




Case 2 cf=p-ix 




Case 3 d^l80°-p-<x. 




Case 4- d'= a.- ji 
borehole problems. 



260 DEEP BOREHOLE SURVEYS AND PROBLEMS 

hence 

V 1 — COS- i cos^ d 

Case 3. — Case 3, Plate XV, shows that in this case the 
form is 

5 = (GO - iS) + (90 - a) = ISO - 13 - a 

consequently 

5 = 180° - ( /i"' + «i"^i_ \ (39) 

Vvl — cos^ i cos- 6/ 

Case 4. — The form assumed in this case is shown in 
Cases 4, Plate XV, to be 

5 = (90 - iS) - (90 - a) = a - iS 

which gives 

5 = Z'"^'-^^"' - (40) 

V 1 — cos^ i cos^ d 

When the hole is at right angles to the strike of the 
bedding, the above four formulae become : 

Case 1.— 6 = ^■ + 5i (41) 

Case 2.-5 = i - di (42) 

Case 3.-5 = 180° - i - 8i (43) 

Case 4. — 8 = 8i - i (44) 

2. To Find the True Thickness of a Bed Knowing Its 
Dip and the Direction of a Borehole in It, also the Distance 
Through Penetrated by the Hole.— Let A2B (Fig. 174 
plan) be the plan of the borehole AB, and A2C2 the direction 
of the strike on this plane (all lines parallel to A2C2 are in 
the direction of strike). A2-D1 is the direction of full dip, 
and AiDi and AD are in the same vertical plane as shown 
also in Fig. 174, end view. The angle d between the directions 
of full dip and of the borehole is shown in its different super- 
imposed positions in the right or projected figure. The 



PROBLEMS 



261 



true dip of the seam 5 is shown by the angle A^DiAi and its 
dip a in the direction of the borehole by the angle A2BA1. 
WXYZ is the horizontal reference plane 

/3 = A2BA = dip of borehole, and by the funda- 
mental dip formula for an apparent dip a and 
true dip 8 
tan a = tan 8 cos 6. 

t = the true thickness of the beds. 





Fig. 174. 



The true length of the borehole AB and its direction are 
found from the core and the survey. 

t = AAi cos 5 

A2B.A2A1 



= {AA2 — AoAi) cos 8 



AB sin 13 — 



A2B 



cos 5 



(45) 



= {AB sin ^ — A2B tan a) cos 8 

= {AB sin i3 — A2B tan 5 cos d) cos 8 

= AB{siia. jS cos 8 — cos /S sin 8 cos d) 

III. Boreholes to Particular Points 
These may be grouped into two suites : 



1. Those set at a definite angle, the problem being to 
find where it will hit a known seam, lode, workings, etc. 



262 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



2. Those which have to hit a given point in a known 
seam, lode, workings, etc., the problem being to find the 
required initial inclination and bearing of the hole. 




Fig. 175. — Borehole assisting subsequent sinking. 

The practical problems connected with these important 
groups of problems arise when it is desirable 

1. To tap known bodies of water, gas, mineral, etc. 

2. To assist in sinking a shaft to known workings and 
thus remove the debris by borehole with trams spotted 
beneath (Fig. 175). 

3. To aid ventilation of seams being worked simul- 
taneously. 

4. To conduct haulage ropes, electric cables, com- 
pressed-air lines or stowage pipes. 

5. To explore for new deposits, etc. 

1. Given a Definite Angle for the Hole and Two Known 
Points in the Stratum to Find Where the Borehole Will 
Strike the Stratum. — A and D (Fig. 176) are imagined as 
being in the same plane as the borehole but need not 
necessarily be as long as they are in the seam or stratum 
being investigated by the borehole; their positions can be 
projected into the borehole plane and a lateral term included 
in the computation finally. 



PROBLEMS 



263 



Let A be an outcrop and D a point in the workings with 
C the base of the borehole 
-BO in the same or projected 
plane. We have given the 
angles a of the borehole dip 
and 7 the surface slope so 
that the apex angles a and 
j8 shown are deduced. We 
desire the length xoryoi the 
known length DA ^ x -\- y. 

X _ DC _ DC-CB 
~ CA 




Fig. 176. 



sin a' sin BAC 



y 



CB • CA sin BDC sin /3 

sin a sin (f + /3) 



sin (f — a) sin /3 

Expanding we get a form comparable with Eq. (27) above 
X _ cot j8 + cot f 
y cot 



Expanding and collecting 
cot f (x + ^) 
Again 



sm a 



- cot f 

X cot a — y cot jS 

sin (f + /3) 



(46) 



sin (f - a') 


sin jS 


sin (f - D) 


sin A 


sin Z) 


sin (r + A) 


X cot jD - 


- cot f 



Expanding as before 



y cot A + cot f 

Cross multiplying and collecting as before 

cot f (x + y) = y cot D — x cot A (47) 

From Eqs. (46) and (47) note that 

X cot a' — 7/ cot fi =y cot D — X cot A 

Now solve for x or y since a',^,D,A, and a; + ?/ are known. 

r/ie Length of the Borehole. — Having obtained either x or y 

(and applying the lateral deviation angle if the points 



264 DEEP BOREHOLE SURVEYS AND PROBLEMS 

D and A have had to be projected into the borehole plane) 
we get the length for this case, where B is an upstream 
derrick floor from outcrop A, by noting that 5 the strata 
dip and 7 the surface slope are known, also a the borehole 
dip. 

Thus A = y + 8 and 8 = 180° - 7 - a 

hence 

£ ^ sin (t + a) 
L sin (7 + 5) 

.-.L^y^^^ ■ (48) 

sm (7 + 0:) ^ ^ 

When the borehole and strata dip against one another we 
get 

L = ^^^^ ^ + f (49) 

sm (a — 7) ^ ^ 

and so on for all the other features such as displacement, 
depth, etc., either normal to the stratum strike or at any 
bearing therewith, by making the necessary lateral angle 
addition to the formulae as in Eqs. (21 and 34). Therefore 
it is scarcely necessary to add these variant cases which 
will be left to the reader. 

2. To Locate a Specified Point in a Stratum, Vein, 
Workings, etc., by Boring to It, i.e., to Find the Necessary 
Starting Inclination and Bearing for the Borehole and 
Therefrom Its Length, Displacement, etc. — This is merely 
the converse of the above case. We now know the dis- 
tances X and y and desire a and jS which are found from 
Eqs. (46) and (47) as before. We solved x and y above as 
a ratio of the known x -\- y, so here we may get a or jS 
as a ratio of their sum which is also known since A and D 
are known. 

It would be redundant to furnish a further example and 
it may be added here that all variant forms of this problem 
can be solved by either Eqs. (46) and (47) above or by Eq. 
(20) on page 247. 



PROBLEMS 
B. TWO-BOREHOLE PROBLEMS 



265 



Two-borehole problems are not very popular and are 
only resorted to when data for more satisfactory methods 
cannot be obtained. This is due to the fact that in all 




Fig. 177. 



-{From "Disrupted Strata/' by the courtesy of Crosby, Lockwood 
& Sons, London.) 



two-borehole computations for the direction of strike of a 
deposit the resulting conclusions are ambiguous and have 
to be supplemented by observational data, usually of a 
geological character, in order that we may decide as to 
which of the dual answers to adopt. 

a. Two Vertical Boreholes. — To obtain the direction of 
strike and amount of dip : The amount of dip is found direct 



266 DEEP BOREHOLE SURVEYS AND PROBLEMS 

from the core by observing the maximum inclination of 
stratification planes in it. If A (Fig. 177) be the deepest 
borehole and is h ft. deeper than B and 8 is the strata dip 
observed from the core, set out a circle of radius h cot 8 
and center A. Draw the two possible tangents from B to 
A such as Ba and Ba' (Fig. 177). As the surface coordi- 
nates of A and B are known we also know ^ba the bearing 
of the line from B to A. The angle BAa, or BAa' = d, 
is the strike angle sought. The contact point lines Aa 
and Aa' of bearings ^a and ^d', respectively, are the possible 
direction lines of the full dip of the stratum. We now get 

Ti' A " 
h cot 5 = B'Ai" and A/,n, = cos d the angle required 



Hence 



or 



, . h cot 8 

cos i^d - ^ba) = ~Jb~ 

, . ]% cot 8 

cos {^BA - M = —Jb~ 



(50) 



The dip a in direction BA can now be found by the funda- 
mental dip formula where a is any apparent dip A'B'A", 8 
the true dip Ai'B'Ai", and d the angle Ai'B'A' between 
them, i.e., 

tan a = tan 8 cos B (51) 

b. Given One Vertical and One Slanting Borehole and 
the Angle the Core Makes with the Bedding to Determine 
the Dip and Strike. — Say the vertical hole A cuts the 
bedding at A' at 5 deg. (Fig. 1, Plate XVI), the slanting 
hole dipping at a from B cuts the bedding at 5i deg. (The 
point B may be moved up so that the apexes of the cones 
about the A and B holes coincide at A', for this does not 
alter the relative angular conditions.) 

Set off a cone at A' having the apical angle of 25 = CA'D 
about AA' and another having the apical angle of 25i = 
EA'F about BA' . The true dip is got from the vertical 
hole as 90 — 8, since the beds make an angle of 8 with 
the vertical. 



PROBLEMS 



267 




Fie. 5 



Plate XVI. — Two-borehole problems. 



268 DEEP BOREHOLE SURVEYS AND PROBLEMS 

The bedding planes make an angle of 8i with the slant 
hole and the locus of all planes satisfying this demand 
is found by the surface of the cone EA'F constructed as 
above. The right cone of the vertical hole A A' is cut by 
the horizontal surface in a true circle and the cone about 
the slant hole of axis BA' is cut by the same surface plane 
in an ellipse as shown. Use any of the well-known methods 
for getting the section of a cone cut by a slanting plane. 
Here the plane slants at a to the cone axis BA'.^ 

Any tangential plane to the right cone CA'D of the verti- 
cal hole will be cut by the vertical hole A A' at 5 deg., 
the angle at which this vertical borehole cuts the bedding. 
Therefore the tangent to both circle and ellipse satisfies the 
demands of both holes. This tangent XX can be drawn 
on both sides, making the problem ambiguous. 

1. The problem has many possibilities dependent on the 
relative sizes and positions of circle and ellipse. Thus 
in Fig. 1, Plate XVI, we have the two possible strikes 
XX and XiXi. Therefore we have only two possible 
strikes when circle and ellipse cut each other. ^ 

2. If however the minor axis of the ellipse equals the dia- 
meter of the circle as in Fig. 2, Plate XVI, we also get a 
definite dual strike solution. Indeed the line connecting 
their centers is also a strike elevated or depressed, but the 
dip may be in either direction. 

3. When the cones do not intersect, as in Fig. 3, there 
are four possible solutions to the problem. 

4. When the cones are externally tangential there are 
(Fig. 4) three possible solutions, and the tangent strikes 
need not be parallel. 

5. When the cones are internally tangential there is 
only one tangent (Fig. 5), we get only one strike and the 
problem is therefore solvable. 

6. Another single solution case arises when the slant 
hole follows the true dip of the strata and is therefore a 
point in plan. If it did not follow the true dip but still 

1 Haddock, M. H., "Disrupted Strata," p. 19, Crosby, Lockwood & Sons, 
1929. 

^LoBECK, A. K., "Block Diagrams," p. 134. 



PROBLEMS 



269 



kept on the dipping surface the point would be displaced, 
giving two solutions for the strike. 

C. THREE-BOREHOLE PROBLEMS 

These are the most favored and oldest of borehole com- 
putations because they provide a convincing proof and 
can be applied also to three given altitudes like outcrops 
at different heights above sea level. 

Three Boreholes Not in Line 

First Solution. — If the holes are not put down from a 
level surface, first reduce the surface level to a given datum 
such as sea level or that of 
the lowest borehole mouth. 
From the survey of the lines 
connecting A the deepest 
hole (Fig. 178) to C the 
shallowest and also from the 
depth yielded in each hole we Fig- i78. 

know the plan length of CA which is CiA, also of CB which 
is EB. We know the respective dips of these lines, 
i.e., a and j8 since AdBiD is on the horizontal plane, 
D being where CB produced meets CiBi produced; 
therefore we also know the plan angles Bi, 6 and 62 between 
these lines, by construction for di and 62 while d is given. 
From the two vertical triangles CCiA and CCiD and base 
triangle ACiD note that 

tan a sin di 




tan 18 sin 62 



= m 



and 



therefore 



61 + ^2 = 180 - = n 



n — 



(52) 

(53) 
(54) 



Substituting m and di in Eq. (52) we get 

sin {n — 62) 



m 



which expands to 



tan 02 



sin 62 



sin n 



m + cos n 
thus giving 62 for obtaining the strike. 



(55) 



270 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



To get the full dip 5, applying the rule of Eq. (52) above 
we get 



tan d sin 90' 



or tan 5 = 



tan (S 



(56) 



tan /? sm ^o sm 02 

so that Eqs. (55) and (56) provide the full solution. 

Second Solution. — This alternate method is adopted 

when we do not desire to obtain the angles di and 62 by 

construction. Let the 
known lines ABi and BE 
equal h and U, also let the 
known depth difference 
between B and A he hi 
and between C and B be 
/i2. Produce ABi (Fig. 
179) to take a perpendic- 
ular DG let fall on it from 

D, and draw BFi and BiFi meeting at Fi each normal to 

AD the strike line so that the angle BFiBi = 5 the full dip. 

DBi = hi cot /? (57) 

DG 




Fig. 179. 



tan 4>2 = 
DG - 



GBi + BiA 

DBi sin 01 



(58) 



and 



GBi = DBi cos 4>i 
By substituting in Eq. (58) we get 

_ DBi sin <pi _ hi cot j8 sin 0i 
tan <p2 — 



tan 02 = 



DBi cos 4>i + h 


/ii cot /3 cos 01 + Zi 


7 ^2 • 
hi-r- sm 01 

/I2 


7 ^2 • 

Ally- sm 01 

/12 


/llf- cos 01 + li 

/12 


~ hil2 cos 01 + hih 
/12 


hih sin 01 





(59) 



/ll?2 COS 01 + /I2/1 

Third Solution. — Using the above figure and notation 
and noting that the bearing of AC is /3i, of BC, ^2 and for 



PROBLEMS 271 

the full rise FC, ^d and h the difference in depth of the 
deepest hole A and the shallowest C: 

h = j—^ r tan /S = CiF tan 5 = ^-^ ^ tan a 

cos {^d — ^2) cos (iSi — /Sd) 



Dividing we get 



Whence 



cos ((3d — 132) = I, ^ tan /? ^ J^ 
cos (iSi — ^d) tan a m 



, ^ cos 1^2 — A; cos j8i .^p.v 

tan 13d = — —. — ^ J — -. — ^ (60) 

sm (32 — k sm jSi 



Which gives the full rise bearing from which /3d + 180 deg. 
is the full dip bearing and the amount of dip can be got from 
the fundamental formula (51), thus 

, , tan (8 

tan d = 



(61) 



cos {(3d — (32) 
or 

tan a 

cos (,81 - ^d) 

First Graphical Solution. — Assume the surface survey 
reduced to level is as shown in Fig. 180 and the stratum 
is 800 ft. deep at A, 550 at B, and 200 at C. 

Plot triangle ACiBi from field notes and erect perpendicu- 
lar CiC on BiCi at Ci and equal to the difference in elevation 
between C and A. On this line measure off CE equal 
to the difference in elevation of C and B. Draw EB 
parallel and equal to CiBi. Connect C and B and produce 
to meet CiBi produced in D. Join AD and draw CiF 
perpendicular to AD; and on CiB lay off CiM = CiF. 
Join C and M. Now CiF is the direction of dip and CMCi 
its amount. 

Second Graphical Solution. — Lay off the surface level 
triangle ABC or the original triangle (Fig. 181) leveled 
to a given datum. Set off at the shallowest and deepest 
holes, A and C, their respective depths AAi, 800 ft., and 



272 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



CCi, 200 ft. at right angles. Join AiCi and on AAi and 
CCi scale off the depth of the hole of intermediate depth, 
i.e., B = 550 ft., so getting Aa and Cc. Join a to c and 
where it cuts AiCi at d erect a perpendicular dE to AC. 
Join EB thus getting the line of strike. From either or 




Fig. 180. 



both of the points A or C drop a perpendicular on to this 
strike line and complete the right-angle dip triangle by 
setting off the depth of the point concerned respecting the 




Fig. 181. 

B depth normal to this line. For example, AF is normal 
to BE the strike and FG = A depth minus B depth = 
800 - 550 = 250 ft. Hence AGF is the amount of dip. 
Check with CH normal to strike and HJ = 550 — 200 = 
350 ft., the difference in depth of C and B. This again 
gives the amount of dip, and its direction is from F toward 
A the lowest point. 



PROBLEMS 273 

Third Alternate Graphic Solution. — This method, which 
is an extension of the third computation method above 
and of the method for two vertical boreholes dealt with 
previously, is the quickest graphical solution of the three- 
borehole problem (Fig. 182). Plot the horizontal posi- 
tions of the boreholes, i.e., draw A,B and C or A,Bi and Ci 
in their true relative positions in plan (Fig. 182). Let hy 



Di reef I on G of Strike 




Fig. 182. 

be the difference in depth of A and C, and h% the difference 
between B and C (here hi is CCi of Fig. 179 above and h^ 
is EC of the same figure). At A as center draw the circle 
of radius r^ = hi cot 5 and at B draw a circle with radius 
7-2 = hi cot 5, the full dip angle 5 being got from the cores. 
Draw the tangents to both circles from the shallowest 
point C and they together will provide one line, so giving 
the strike bearing and thus the dip bearing by +90 deg. 

Special Cases of the Three-borehole Problem 
Two special cases arise in practice, viz. : 

1. When all the boreholes hit the stratum at the same 
altitude respecting the datum; we shall not deal with this 
case which presents no features of note. 

2. When Two of the Holes Hit the Stratum at the Same 
Altitude, the Other Being Either Higher or Lower Than 
These (Fig. 183). — ^Let A and B be the two boreholes 
of similar depth respecting the datum. Pass a horizontal 
plane through AB which is the strike of the stratum and it 
will cut the C borehole, here assumed shallower, in Ci. 
Drop perpendiculars from C and Ci on to A B at F. The 



274 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



angle CFCi = 8, the full dip of the stratum. The angles 
^1 and a also the lengths ACi and CCi are known. 



and 



or 



tan 5 = 



FCi 


= ACi sin di 




cc. 


CC, 


tan a 


FCi 


ACi sin di 


sin di 



tan 8 = tan a cosec di 



(62) 



Given Three Deviated Boreholes to Determine the Dip 
and Strike of the Stratum. — Having surveyed three bore- 




FiG. 183. 

holes A, B and C and found their net horizontal displace- 
ments and depths a line may be drawn in a direction 
connecting the source and end of each. This line will 
usually be the shortest line between these points and will 
have the average deflection of the hole throughout. 

Let us consider a concrete case of three holes set vertically 
but now deviated until when reduced as above we get their 
bases data also. Let the surface and borehole data be: 





Coordinates 


Net bearing 
of hole 


Length of 
hole, feet 


Dip from 

horizontal (90 — 

off vertical), 

degrees 




X 


Y 


A 
B 
C 


1,000.00 

100.00 

-600.00 


500.00 

-800.00 

200.00 


N.50°E. 
S.80°E. 
N.10°E. 


1,200 
300 
400 


60 
75 
80 



These points are set out in ABC (Fig. 184), 



PROBLEMS 



275 



Set off from A a line at the hole bearing N. 50°E. and on 
it the dip angle of the hole, i.e., 60 deg., setting off on the dip 
line A Ax = 1,200 ft. the borehole length. Drop a per- 
pendicular A1A2 to meet the direction line from A in A 2, and 
Ao will be the plan position of the end of the borehole from 
A. In a similar manner, using the relevant data, get B2 



^*^. 




Fig. 184. — The three slanting borehole problem. 



and Ci . AoBoCi is the actual area encompassed by the bore- 
hole bases. On line A2C2 set off the depths of A2 and C2 
at these points, respectively, at right angles to this line, 
so getting As and C3. Join A3 to C 3 and produce to meet 
A2C2 produced in x. (Note that A2A3 is the depth of A 2 
and 52^3 is that of Bo and C2C3 that of C2.) Similarly set 
off AoA^, the depth of A2, and B2B3, the depth of B2, 
at right angles to ^2^2 as shown. Connect A' 3 to B3 
and produce to meet A2B2 produced in y. x and y are on 
the strike of the stratum. Drop a perpendicular C2D 
on to the strike line xy and erect one, C2E, at C2 equal to its 
depth. Join ED and the angle EDC2 is the amount of dip 
and its direction is DCo. Check by B2 GF using the same 
reasoning. 



276 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



^Off Vertical 
Angle 



NOMOGRAPHIC AND ALIGNMENT METHODS 

These simple and easily understood charts are becoming 
more and more popular because they can, as a rule, be 
manipulated by the boring personnel and others who wish 
to save time. 

Figure 185^ shows the well-known versed-sine relation 
which can be applied to a hole the deviation of which is 
either regular or can be approximately meaned throughout 
its course, giving a straight deflection; that is to say, a 
constant off -vertical angle. The alignment chart itself 
(Fig. 186) is constructed by putting on the left 
the logarithmic scale A with the scale of versed 
sines Bi or Ci on its right and the vertical 
correction scales corresponding at B2 and Co- 
To get a correction, place a straightedge 
at the desired depth of hole on A scale, say 
100 ft., and at the proper off-vertical angle on 
Bi scale; continue and read off the correction 
on B2 or C'z scale. If the straightedge falls 
off scale B2, then use scales Ci and C2. If the 
measured depth is greater than scale A divide 
it by 10 and multiply the corresponding results 
on B2 or C2 by 10. Thus if the depth is 2,500 
ft. and the off-vertical angle 10 deg. use 
250 ft. and multiply the resultant vertical correction of 
3.75 ft. by 10, giving 37.5 ft. Use a transparent cellu- 
loid straightedge with a fine black parallel line near one 
edge. 

Based on Fig. 185 Mr. BrindeP discusses a simple employ- 
ment of mathematical tables and formula, noting that 

1. By the Cosine Method. 
The corrected measurement = (actual measurement) X 

(cosine of off- vertical angle), 
i.e., in Fig. 185 AB = AD 
cos BAD. 

1 Brindel, H. F., Oil Gas Jour., p. 41, Apr. 11, 1929. 

2 Ibid., p. 41. 




Fig. 185. 



PROBLEMS 



277 



2. By the Versed Sine Method. 

The corrected measurement = (actual measurement) — 

(actual measurement X ver- 
sine of off-vertical angle) 
i.e., BC - AD vers BAD. 



S3!|cldD3l6u\/ L|0IL|MO+43aj Ul |K)AJ3^UI 




0C3OO O C5 O O <0 O 

oooo C3 o o u^ o in _ 
OCVX>t~ iD tn ^ ro ro ex c-J 



— olo oo o o ooo o 
Lo Oo oo CJ o cyi^ o LD — _. 

— ""O cor- "^ "^ ^r<->pO Cvl Cvl — "— 



S8!|ddD ai6u\^ Moimm o+ +a3j U} iioaj94.u£ 



278 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



A table of natural cosines and another of natural versines 
should be kept, the latter being the simpler to use having 
least multiplying figures. A check on each of these 
methods would be always advisable; e.g., in a 200-ft. hole 




Fig. 186.- 



-190 
-3100 

-Alignment chart for determining vertical corrections in crooked 
holes. 



5 deg. off the vertical the cosine rule will give a correct 
vertical distance of 199.24 ft. and the versine rule will 
give the same. Table IX^ shows tabulated data, the 
results of several such examples as the above. 

Plate XVII shows Milliken's chart^ for the graphic 
determination of vertical corrections in crooked holes. It 
is drawn on logarithmic paper, the off-vertical angles being 

^ By the courtesy of R. Van A. Mills, of Petroleum Engineering. 
2 Charles V. Milliken, of the Amerada Petroleum Corporation, in Oil 
Gas Jour., p. 102, 1930. 



PROBLEMS 



279 



represented by diagonal lines. The measured interval 
scales are shown on the left and right margins. Pick off 
the proper measured interval on the left or right margin 
and follow the horizontal line from this point on the meas- 
ured interval scale to its intersection with the proper 
off -vertical line. From here follow a vertical line to the 
upper or lower margin, as the case may require, where 
the vertical correction in feet is indicated. 



Table IX. — Example and Fokm of Notes for Versine Vertical 
Correction Method 



Measurement 
from point of 
last measure- 
ment, feet 


Off-vertical 
angles, 
degrees 


Factor, 
natural 
versine 
of angle 


Vertical 

correction, 

feet 


Corrected 
measure- 
ment, feet 


Total true 

depth, 

feet 


200 
190 
195 
220 
240 
238 
242 
256 
239 
250 


5 

10 

24 

6 

15 

7 

9 

6 

30 

25 


0.0038 
0.0152 
0.0865 
0.0055 
0.0341 
0.0075 
0.0123 
0.0055 
0.1340 
0.0937 


- 0.76 

- 2.89 
-16.77 

- 1.21 

- 8.18 

- 1.79 

- 2.98 

- 1.41 
-32.03 
-23.43 


199.24 
187.11 
178.23 
218.79 
231.82 
236.21 
239.02 
254.59 
206.97 
226.57 


199.24 

386.35 

564.58 

783.37 

1,015.19 

1,251.40 

1,490.42 

1,745.01 

1,951.98 

2,178.55 


Total 2,270 






-91.45 




2,178.55 



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A.I.M.M.E. American Institution of Mining and Metallurgical 

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M. Mag. Mining Magazine, London. 

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281 



282 DEEP BOREHOLE SURVEYS AND PROBLEMS 

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N.S.K. Neftianoe i Slantzenoe Khoziaistvo, Moscow. 

O.A. Oil Age. 

O.B. Oil Bulletin. 

O.B.Z. Osterreichische Zeitschrift. Berg-und Hlittenwesen, 

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O.F.E. Oil Field Engineering, Philadelphia. 

O.G.J. Oil and Gas Journal, Tulsa, Oklahoma. 

O.V.B. Organ des Verein dor Bohrtechniker, Vienna. 

O.W. Oil Weekly, Houston, Texas. 

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P.A.G. Pan-American Geologists. 

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P.E. Petroleum Engineer. 

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288 DEEP BOREHOLE SURVEYS AND PROBLEMS 

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290 DEEP BOREHOLE SURVEYS AND PROBLEMS 

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INDEX 



Absolute check on survej^s, 53 
Accuracy of borehole surveys, 50 
Acid-bottle record, 53, 95 
Action of gyrocompass, 208 
Advantages, of fluid methods of 

survey, 97 
of seismic methods, 245 
Alignment charts for deviated holes, 

276, 278 
Ambronn, A., cited, 34, 229 
Anderson, A., quoted, 5 
Anderson's apparatus, 200 
Anschiitz apparatus, 216 
Anschiitz-Kaempfe's device, 10 
Anschiitz-Kaempfe's gyrocompass, 

206 
Apsidal angle and plane, 114 
Atwood's apparatus, 176 
Audible or acoustic device, 11 
Auxiliary registrations, 22 
Axial dip in gyrocompass, 211 
Azimuth gyroscope, 204 



B 



Bailing ropes, 1 

Basket or lantern method of plumb- 
ing, 41 
Batteries, drj^ 177, 179, 183 
Bawdon's apparatus, 134 
Bearing of boreholes, 264 
Benzine wash, 181 
Bibliography, 283 

Boreholes not at right angles to 
strata strike, 255 
to particular points, 261, 262 
at right angles to strata strike, 
248 
Briggs' clinophone, 141 



Briggs' horizontal clinoscope, 33 
Briggs' transmitter and receiver, 141 
Brindel's chart, 276 
Bubble log and oscillations, 224 
Burbach borehole pressure recorders, 
31 



Californian boreholes, 5 

Camera devices, 78, 176, 179, 186, 

223 
Casing, 10 

Centering devices, 153, 156, 164 
Channing Park, cited, 8 
Chanslor-Canfield borehole model, 

39 
Check surveys, 53 
Circulating water, 10 
CHnographs, 101, 220, 224 
Clinometers, 104, 193, 198 
Clinophone, 141 
Clockwork, 59, 81, 87, 110, 123, 132, 

137, 151, 156, 161, 220 
Comparison of methods of survey, 

52, 53 
Compass methods, 121, 139, 181, 193 
Conductivities of rocks, 230 
Constrained gj^roscope, 205 
Continuous registrations, 22, 30, 

36, 84, 94, 126, 145, 161, 166, 

193, 223 
Controller, 196 
Cooke, Prof. L. H., cited, 19 
Copper sulphate method, 114 
Core orientation, 48, 54 
Core spin, 19 
Correction device, 184 
Cosine method, 276 
Costs of borehole surveys, 50 
Counter-dip borehole problems, 248, 

249 



291 



292 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



Curvature, incipient, 10 

Czuchow borehole, Upper Silesia, 25 



D 



Deep boreholes, 1, 8 

Denis-Foraky teleclinograph, 166 

Depth recorders, 26, 28 

Deviation, angular, 2, 274, 275 
causes of, 1, 15 
factors influencing, 54 

Diagrams, 170 

Diameters of boreholes, 18, 28, 29 
change in, difficulties due to, 29 
irregularities in, 29 
shrinkage, causes of, 29 

Diamond-drilled holes, 3 

Dickenson, J., cited, 18 

Difficulties due to diameter change 
in boreholes, 29 

Dip, of boreholes, 49, 250, 260, 264 
of strata, 22, 96, 177, 179, 256 

Direction of beds, 256 

Disadvantages of fluid methods of 
survey, 97 

Displacements, and depths of bore- 
holes, 250, 251, 253, 264 
horizontal and vertical, 2, 3, 6, 
184, 203 

Dixon's gyrocompass device, 85 

Double pendulums, 211, 162 

Driftmeter, 151 

Driftmeter record, 53 

Drum devices, 190, 196 



E 



Electric coring, 231 
Electrical geophysical methods, 225 
Electrical liquefaction of gelatin, 109 
Electrical methods of survey, 47, 

111, 113, 156, 166, 127, 148 
Electrolytic registration, 113 
Electromagnetic examination of 

ground, 226 
Electromagnets, 158, 168 
Equator and gyro-action, 209 
Equi-potential lines, 145 
and methods, 226, 227 



Equi-potential surfaces, 231, 232 
Erlinghagen, O., quoted, 41, 76 
Erlinghagen's apparatus, 156 
External photographic devices, 176, 
179 



Films, 175, 177, 179, 183, 189, 221 
Fissured strata, 18, 182 
Florin's method, 77 
Fluid methods, 47, 95 
Foraky depth recorder, 26 
Foucault's law, 204, 212 
"Freedom" of gyroscope, 205 
Freezing-shaft holes, 7 
Freise, F., cited, 62, 64, 76, 136 



G 



Gallacher's apparatus, 137 

Gelatine, 63, 102, 108 

Geological causes of deviation, 17 

Geophone, 240 

Geophonic or seismographic meth- 
ods, 48, 240 

Geophysical methods of borehole 
survey, 225 

Goniometers, 105, 108 

Goodman's apparatus, 80 

Goodrich, H. B., quoted, 6, 203 

Gothan's stratameter, 64 

Graphical problem for boreholes, 271 

Gravitation, 208 

Ground wave coefficients, 234, 235 

Gudgeon joints, 164 

Guide rods, 191 

Guide springs, 154, 188 

Gyro-axis, 209, 210 

Gyrocompass, 204, 211, 214, 217 

Gyroscopic compass methods, 204 

Gyrostatic methods of survey, 48, 
83, 85, 204 



H 



Haddow's method, 121 

Hall and Armentrout's device, 83 

Hanna's inertia-rotor apparatus. 87 



INDEX 



293 



Hardness, of common minerals, 16 

of strata, 15 
Hatch, Dr. F. H., quoted, 182 
Haussmann, Dr. K., quoted, 206, 

216, 220 
Haussmann's apparatus, 185 
Heiland, Dr. C, quoted, 245 
Hillmer's apparatus, 136 
Hoffmann, J. I., quoted, 183, 185 
Horizontal boreholes, 32 

problems, 253 
Hydrofluoric acid, 97, 98, 108 



Illumination of borehole walls, 177, 

179 
Inclined strata, 17 
Incorrect centering at surface, 15 
Incorrect plumbing adjustment, 45 
Inclination measurer (Haussmann's), 

188 
Inclined borehole problems, 250 
Inclinometer, 171 
Inertia-rotor method of survey, 48, 

87 
Inexpert tiller work, 29 
Inking device, 174 
Instrumental survey of boreholes, 46 
Irregularities in borehole diameter, 

29 



Jahr's depth and thickness method, 

22 
Jarring at core, 20 
Jennings, J., quoted, 19 
Justice, J. N., cited, 8, 31 



K 



Kegel's apparatus, 146 
Kendall's apparatus, 58 
Kiel Nautical Instrument Com- 
pany's apparatus, 211 
Kind's method, 55 
Kinley's apparatus, 171 
Kiruna method, 113 



Kitchen, Joseph, quoted, 2, 8, 17 
Koebrich, A, cited, 55 
Koebrich's apparatus, 60 
Koerner's borehole survey device, 

153 
Koerner's core orientator, 74 



Laboring of rig gear, 10 

Lahee, Prof. F. H., quoted, 37, 54 

Lame's coefficient, 235 

Lamps, 177, 188 

Lapp's core orientator, 74 

Lapp's stratigraph, 25 

Latitude and gyro-action, 209, 212 

Lengths of boreholes, 248, 250, 252, 

263 
Lesser deflection records, 41 
Levels, 191, 220 

Literature index abbreviations, 280 
Log checks, 9 
Love's waves, 237 



M 



Maas' method, 108, 109 
Macfarlane's apparatus, 111 
MacGeorge's clinograph, 101 
MacGeorge's clinometer, 104 
MacGeorge's core orientator, 63 
MacGeorge's guide tube, 107 
Macready, G. A., quoted, 48, 55, 92 
Macready's method, 91 
Magnetic needle methods, 47, 80, 

88, 91, 99, 102, 113, 132, 134, 

138, 194 
Magnetism of rods, 19 
Magnets, 191 
Maillard's apparatus, 148 
Malamphy's seismic method, 240, 

242 
Manometer, 32 
Marriott, H. F., cited, 15 
Marriott's continuously recording 

device, 126 
Marriott's intermittently recording 

device, 128 
Martienssen, Dr. 0., quoted, 216 



294 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



■ Master borers, 9 

Maximum and minimum thermom- 
eters, 35 
McCutcliin, J. A., quoted, 36 
McLaughlin, R. P., quoted, 52 
Meine's borehole survey apparatus, 

109 
Meine's stratameter, 67 
Meridian, true, 209, 212 
Messenger weights, 67, 75 
Methods of surveying, 47, 54 
MilUken's deviation chart, 277 
Models of boreholes, 38 
Moh's hardness scale, 15 
Mollmann's apparatus, 131 
Mommertz low temperature bore- 
hole thermometer, 35 
Moreni oilfield borehole, 1 
Mud pressure, 54 
Multiple photographic devices, 47, 

94 
Murphy, P. C, and S. A. Judson, 
cited, 50 

N 

Neighboring boreholes, 17 
Nolten's apparatus, 98 
Nomographic methods, 276 
North German Deep Boring Com- 
pany's stratameter, 71 
Nutation, 208 

O 

Oehman's apparatus, 182 
"Off-vertical" angle, 50, 184, 276, 

279 
Ohm's law, 232 
Oil wells surveyed, 5, 6 
Orientating, of cores, 48, 54 

couphngs, 117, 118, 158, 171 
Otto-Gothan apparatus, 123 
Oversetting diamond crowns, 18 
Owens' apparatus, 193 



Packing rings, 179 
Payne-Gallwey cited, 182 
Pendulum methods, 47, 153, 166, 
168, 173 



Penetration distance from cores, 

etc., 260 
Penetration point computations, 

246, 262, 264 
Petersson, Prof. W., cited, 113 
Phials, 102, 108 
Photographic methods, 47, 77, 93, 

153, 166, 168, 173 
Pilot wedges, 184 
Plans of drill holes, 7, 38, 52, 172, 

192, 202 
Plastic cast method, 48 
Plotted surveys of boreholes, 3, 

7, 32, 38, 41, 52, 107, 119, 131, 

162, 186, 199 
Plotting borehole data, 37 
Plumb-bob methods, 88, 121, 126, 

128, 134, 136, 137, 141, 148, 

182 
Plumbing by lantern-basket method, 

41 
Plumbing cylinder, 187, 216 
Plummet and magnetic needle meth- 
ods, 47 
Plungers, 77, 30, 147, 151 
Poisson's constant, 234 
Polarization by Schlumberger, 228 
Potential method, 226 
Practical problems with boreholes, 

262 
Precession, 205, 206 
Precipitation method, 112 
Pressure on rods, 18 
Pressure records, 31 
Pricker or plunger methods, 48, 

73, 75, 123, 136, 151, 161, 163 
Problems, 246 
one borehole, 246 
three boreholes, 269 
two boreholes, 265 
Profiles or sections of boreholes, 37 
Progress records, 22 
Progress reports, 10 
Purposes of boreholes, 50 

R 

Rand boreholes, 2 

Rankine, Dr. A. 0., quoted, 238, 
243 



INDEX 



295 



Rapoport's method, 76 

Rayleigh waves, 237 

Recorders, 160, 169, 172, 187, 219 

Records, 192, 196, 198 

Redmayne, Sir R. A. S., cited, 55, 

64, 112 
Reduction of borehole diameters, 18 
Registering apparatus, 189, 219 
Reinhold's apparatus, 179 
Requirements for successful survey, 

46 
Rigidity, of gyrocompass, 209, 222 

of rods, 17 
Rod abrasions, 10 
Rods, 1 

Rope recorders, 36 
Rotation of rods, 20 
Riihland's apparatus, 100 
Rumanian boreholes, 4 
Rumpf and Kleinhenn's apparatus, 

29 
Russian boreholes, 4 



S 



Sag of plumbing rope, 45 
Schlumberger brothers quoted, 227 
Schlumberger's method, 229 
Schmidt, Prof. F., quoted, 41, 44 
Scoring of core-box or casing, 10 
Seismic methods, 233, 236, 242 
Seismograms, 237, 239 
Seismograph, 239 
Seminole oilfield boreholes, 6, 52 
Shaped notches, 47 
Shortest borehole of all, 255 
Shortest possible borehole at given 

bearing, 254 
Sinking shaft borehole, 262 
Six's thermometer, 35 
Slanting boreholes, 255, 266, 274 
Small boreholes, 18 
Small diameter instrument (Kiruna), 

113 
Snow, D. R., cited, 6 
Special joints, 162 
Special three borehole problems, 273 
Specific resistivity of rocks, 230 
Sperry gyrocompass, 83, 220 



Sperry-Sun apparatus, 220 
Sperry-Sun Company's borehole 

model, 40 
Spin of boring tools, 20 
Spinning axis, 205 
Spontaneous polarization, 223 
Static electricity of rods, 19 
Strata profiles, 9 
Stratameter, Gothan's, 64 

Meine's, 67 

North German Company's, 71 

Thurmann's, 70 
Stratigraph, Foraky's, 27 

Jahr's, 22 

Lapp's, 25 
Strike of bedding, 248, 256 
Strip films, 91, 157, 173, 177, 179, 

183, 189, 221 
Stiitzer, Dr. Otto, quoted, 1 
Surface receivers, 169, 219 
Survey of boreholes, instrumental, 

46 
Surwel gyroscopic clinograph, 220 
Swedish clinometer-goniometer, 105 
Switches, 190 



"Take-up" motor, 213 
Teleclinograph, 166, 171 
Temperature measuring devices, 34 
Thermal surveys, 34 
Thermometers for boreholes, 35, 222 
Thickness of beds, 256, 260 
Thiele, P., cited, 33 
Three-borehole problems, 269, 271 

all slanting, 274 

special cases, 273 
Thurmann's borehole model, 39 
Thurmann's borehole survey appara- 
tus, 162 
Thurmann's stratameter, 70 
Time-travel curves, 244 
Timing device, 200 
Torque, 205, 206 
Total depth problems, 252, 253 
Tjansmitters, 171, 216 
Transverse seismic waves, 235 
True dip, 256 



296 



DEEP BOREHOLE SURVEYS AND PROBLEMS 



Two slanting boreholes, problem, 

268 
Two vertical boreholes, problem, 268 
Types of surveys, 48 

U . 

Upham and Dixon's gyrostatic ap- 
paratus, 85 
Upstream boreholes, 250, 252 
Upward deviation, 31 



Van Orstrand, C. E., cited, 36 
Versine method, 277 
Vertical borehole problems, 248 
Vertical correction, 6 
by alignment chart, 279 



Vibrometer, 239 
Vivian's method, 57 

W 

Wache's plumbing device, 42 
Walls of borehole photographed, 

177, 179 
Waves, electrical, 226 

seismic, propagation of, 235, 243 
Weak core barrels, 18 
Wheatstone's gyroscope, 204 
White, E. E., cited, 108 
Wire plumbing, 42 
Wiring diagrams, 142, 145 
Wolff's apparatus, 59 



Z 



Zenith angle and plane, 114